General Questions:
■Is the Druid class for me? What are Druids like to play?
Druids are the true kings of the Hybrids classes.
Capable of filling the roles of Ranged DPS (Moonkin aka Boomkin), Melee DPS (Cat Form), Main/Off Tank (Bear Form) and Healer (Tree of Life) just as competently as any other class.
Druids are quite a simple class to begin with but increase in difficulty as you progress.
It should become apparent as you read through the talent various builds given below that there is allot of common ground between the different specs and its only in the selection of a few talents that shifts the druid in one direction or another
■What is the fastest way to level a druid?
Feral is commonly regarded as the fastest level spec, though some argue that at higher levels Balance equals or overtakes it in terms of leveling speed.

A quick break down of where to spend talents to give the fastest possible leveling speed is as follows:
At level 21, At level 32, At level 50 (this will involve a respec), At level 61, At level 71. After level 71 you can place your talents where you like or respec to your desired final build

If you prefer to level Balance as an alternative to Feral, I advise waiting until you reach Outland (~lvl58) before switching. While its prefectly possible to level from 1-80 as balance, the earlier levels can be particularly painstaking. If you do level balance pre-outland use the level 58 build as a guide to aim for.
level 58, level 60, level 70, level 79
■Which Heirlooms should I use to level my feral druid?
Weapons
There are no feral specific Heirloom weapons, so there's a couple choices (Keep in mind these can be enchanted with old-world enchants, Crusader is pretty helpful for leveling):
Balanced Heartseeker
You won't find any good offhands, but this will give you decent stats for a one-handed weapon.

Grand Staff of Jordan
This will give you +hit and +stam, both useful while leveling. The spellpower will be somewhat wasted, but your self heals will tick a little harder.
Due to the lack of heirloom weapons, simply using regular weapons while leveling may be a wiser choice.

Shoulders

Exceptional Stormshroud Shoulders
Granting Resilience and Agility, these are probably the right choice for tanking lowbie instances.
Stained Shadowcraft Spaulders
Granting AP and +Hit, these are probably the right choice for solo kitty grinding.

Trinkets
Swift Hand of Justice
Makes a nice Trinket Spot filler, may reduce downtime. Equipping 2 of these will net a decent amount of health return while grinding.
■Am I ready for Heroics?
Ideally you should have the best gear possible from all the normal level instances before entering heroics. That said, once you have reached level 80 there is only really 1 way to find out if you are ready and that’s to get stuck in and try them. Start with The Nexus, Utguarde Keep and The Violet Hold as they are among the easier Heroics.
■Am I ready for Naxx10/25?
Again this is similar to the heroics question. Ideally you should be geared in as many Heroic Blues, Epics and badge loot as you as you can.
2 good sites that may help you estimate your readiness are: http://www.wow-heroes.com/ and http://be.imba.hu/
However be warned that these are merely an estimation on the readiness of your gear, not on your ability as a player. That takes time, practice and usually plenty of mistakes.
■Are Druids good enough to Main Tank / Heal / DPS competitively?
A properly specced and geared Druid is fully capable of filling almost every role within a group/raid.
Played and geared right a druid will perform, as well and in some cases better than any other class

Balance Specific Questions:
■Is Balance a good leveling spec?
It is not suggested to spec over to Balance until you are headed to Outlands or basically at level 58 or higher. Balance leveling will allow you to kill single mobs quite rapidly and also bigger packs once you get to the AoE spells. You also have the advantage of being able to control a lot of enemies thanks to root, hibernate (beasts/dragonkin) and cyclone (level 70). However you rely on your mana pool to do damage, and will rely on it too for healing. This means that you will occasionally have to stop to drink and thus creates a certain amount of downtime. Try to extend your mana pool through use of Innervate and more efficient spells such as Starfire (DoTs should not be used unless they go for there entire duration before the mobs dies).
The specs to use, from level 58 onwards are as follows: level 58, level 60, level 70, level 79
■What spec should I be using for maximum dps?
I'd use this base : 3.2 Base Build
It gives you all the most important single target and utility talents, with a few free points that will allow you to choose between(in order of best improvement) :
- more mana regeneration : Intensity > Dreamstate > Moonglow
- more AoE: Gale Winds, Typhoon, Starfall
- more single target damage : iIS > Starfall > Brambles > OF (those are in the range of 1-2% or less increases which why I consider them optional)
■What Glyphs should I be using?
For pure dps purposes use:
■Glyph of Starfire

■Glyph of Moonfire

■Glyph of Insect Swarm
If your guild wants you to keep the hit debuff associated to IS, then you'll have a choice between Innervate and Starfall mainly. None of them are really interesting to be honest.
■What spells should I be using, in what order and when?
With the changes in 3.2 the rotation has changed quite a bit, but in many ways has been simplified. You can choose to start with either the Wrath or Starfire spells to proc Eclipse. I personally use Wrath to start it off as that is what I'm most familiar with.
■Insect Swarm
■Moonfire
■Wrath (till Lunar Eclipse)
■Starfire (till Solar Eclipse)
■Refresh DoTs outside of Eclipse.
Note: If you have the 2T9 set bonus and/or the Idol of Lunar Fury refresh Moonfire as it goes down.
■What sort of gear should I be aiming for?
While leveling:
■SP > Crit > Int > Stam
Once at 80, in a PvE perspective:
■Hit (to cap)> Spell Power > Crit/Haste > Int > Spirit > Mp5
In terms of main stats you'll only be looking for Int and Spi for mana regen.
To help you decide what gear to get and where you can get it, you can use http://www.wowhead.com/?items and take advantage of its item filtering system. For convenience click on the link provided to see Moonkin Gear or as an alternative if you are struggling to maintain the Hit Cap then this Moonkin Hit Gear should cover most things
■How much Hit Rating do I need?
Hit cap for a Boomkin is 17% (~448 rating @ 26.3 rating per %).
Balance of Power drops this by 4% to 13% (~342 rating) .
With the use of iFF or Misery it further drops by 3% to 10% (~263 rating).
If you have a Draenei in your group(must be in group not just in raid) it drops by 1% to 9% (~237)
Note: The Balance of Power currently reads as 6% bonus hit, this is a typo on Blizzards part and has been proven to still be only worth 4% hit rating.
■Which is better Crit or Haste?
In terms of %, Crit and haste are actually quite near to each other, with haste being slightly better (but causing more mana drains). This matters when comparing talents like Celestial Focus, Improved Faerie Fire and Improved insect Swarm.
On a piec of gear Haste will be a better stat to look for until you hit the haste cap which is ~400 haste rating. After this point both crit and haste rating are worth very much the same with a slight lead placed towards crit.
■What way should I enchant my gear?

Head – Arcanum of Burning Mysteries
Shoulder – Greater Inscription of the Storm
Chest – Powerful Stats
Bracer – Superior Spellpower
Weapon – Mighty Spellpower(1 Hand) or Greater Spellpower(Staff)
Gloves – Exceptional Spellpower
Belt – Eternal Belt Buckle
Legs – Brilliant Spellthread
Boots – Icewalker

Note: The weaker versions of these are perfectly acceptable on lower level gear.
Note2: The crafting professions are generally better to use if you have them.
Note3: It has been proven that taking a run speed enchant for your boots can end up being more of a bonus then hit/crit enchant on boots. Premise being that it allows you to reduce the travel time on mobile fights. It also gives you slightly more survivability in being able to get away from "bad stuff" faster.
■What way should I gem my gear?
Gems :
Meta - Chaotic Skyflare Diamond
■Hands down the best in socket no matter how you look at it. If you have a meta socket this needs to be in there.
Red - Runed Cardinal Ruby
■This is the best red socket gem in the game for us.
Yellow - Potent Ametrine or Runed Cardinal Ruby
■Runed Cardinal Ruby is the best gem to place in a yellow socket unless the socket bonus will give you 3 SP per socket you wish to swap the ruby out for at which point you would use Potent Ametrine.
Blue - Purified Dreadstone or Runed Cardinal Ruby
■This is the tricky one of the bunch. If you have the Meta you will only want two of these. If you do not have a meta or already have 2 blues filled then gem Runed Cardinal Ruby in these sockets unless the socket bonus will be 8+ SP.
Jewel Crafters gemming
■Place Runed Dragon's Eye's in every Red socket that gives you Spell Power bonus first. Crit bonus second. Haste bonus third.
■Otherwise Follow the above gemming guidelines.
Note: Due to the relative ease in acquiring Epic gems through PvP (10k Honor) and PvE (10-20 Hero badges) I only have info for the epic gems.
Note2: You are not required to socket a gem that is the same color as a socket you are putting it in. You only do that when socketing for the bonus.

Pure Melee dps build:
http://www.wowhead.com/?talent=0ZEG0cfrz0eo0huAo0Eczb

Melee rotation:
Bosses: Ravage, Mangle, Rake, Shred, Savage Roar, Tiger Fury, Berserk, Shred, Shred, Mangle, Rake, Rip, Shred spam.

Multi Trash: Ravage, Savage Roar, Swipe, Tiger fury, Swipe spam.

Good glyphs:
Rip (must have)
Mangle (good)
Rebirth for raid utility, Maul or FR for help OTing.

Pure tank build:
http://www.wowhead.com/?talent=0ZxGGscrzceRIczVo0E0z
(just imo, others I'm sure will differ. Personally I don't think Primal Tenacity is worth it but it is a tank / pvp talent).

Tank rotation:
Bosses: Enrage, Feral charge, Fairie Fire, Maul, Mangle, Lacerate. Keep mangling and mauling and use lacerate or swipe if max lacerates. Keep refreshing lacerate when needed.

Multi Trash: Enrage, Feral Charge, Spam Swipe and Maul.

Good glyphs:
Maul (must have)
Frenzied Regen (good)
Rip for when dpsing or rebirth for rail utility.
Challenging Roar minor is a must have as well.

Good hybrid build:
http://www.wowhead.com/?talent=0ZxGMsfdzceRc0uAo0Eczb
(what I personally feel is the best build, swap a point in shredding attacks or imp mangle for Primal Precision if you need the expertise)

Solid moonkin build:
http://www.wowhead.com/?talent=0xRbuiIocdhVhRhZMxcub
(personally would use typhoon, starfall and 2 points in dreamstate, don't care what anyone else says, starfall is a great spell for added AoE dmg and if you cant judge the range then you aren't a good moonkin)

Imo rotation:
Bosses: Insect Swam, Moonfire, spam wrath, Spam StarFire on Ecclipse.
Multi trash: Starfall, Hurricane.

Good glyphs:
Moonfire (must have)
Starfire (must have)
Innervate for extra dps, rebirth for raid utility, Insect Swarm for extra dps.

Good resto build:
http://www.wowhead.com/?talent=0VG0uZZf0IubuxquAhst
(think this is considered a cookie cutter style build, although I know there's lots of great variations)

Rotation:
Tanks: regrowth, Rejuv, Lifebloom. (refresh LB on last tick, refresh regrowth when at 2-3 seconds).
Raid: rejuvs and LBs and Wild growths. (with the 0.5 sec less cast time from Nature's Grace you can spam Regrowths onto the raid in emergencies but it's a heavy mana dump).

Good glyphs:
Swiftmend (must have)
Regrowth (must have)
Lifebloom is ok, Innervate is awesome, Rebirth is ok.

I know there's peeps out there with better knowledge than me so feel free to add your thoughts.