Are they good? Yes, 9/10
Who can/can't they handle 1v1? Can handle any class in 1v1 except hunters will cause you some trouble. Can't really solo any decent healers unless you can freecast and get retarded RNG luck with crits.
How is the damage? 9/10
What should I stack? Experiment with different builds and see what you like. My opinion is crit/int build is bis, but I've heard people say haste/int build would be the way to go. I wouldn't agree with this 100%, given the fact that it's pretty hard to find enough haste in this bracket to make it worth anything. Crit/int build doesn't hurt your damages consistency too much, but with a decent crit rating you'll find it easier to burst down your enemies. If you roll a troll, max haste build with berserking + natures grace + lifeblood popped sounds like a rapeworthy combo

Then again, popping all those with a crit set will probably do just as good.
TLDR; crit/int or haste/int are both viable, see which one you like more.
Not class related
What server should I play on? Aggramar EU on horde, Twisting Nether or Spinebreaker on alliance. TN or spine are not nearly as active as aggramar, but all of these realms have an active f2p twink community to play with. (note: Twisting Nether is a pretty big realm, so you will probably encounter some server queues to log on at peak times)
Extra questions, well you're gonna have to decide which race to go so about that: I'd probably go tauren over troll if you roll horde, since warstomp is one of the best racials around, both defensively and offensively. Trolls racial Berserking which is 20% haste for 10 seconds on a 3min cooldown is not bad either, but the somewhat long CD and short duration put me off a bit.
For alliance it's a tough call between nelf and worgen, but seeing how druids are extremely mobile already and moonkin survivability has received some severe nerfs (moonkin form nerf, battle fatigue = rather weak rejuv), I would go nelf for smeld which is an excellent cooldown to suspend incoming burst / cc. Then again, Darkflight is not bad either, combined with displacer beast and travel form you'll make some lightning speed getaways, and the additional +1% crit worgens get is a nice bonus.
Sorry for the last paragraph, probably won't help you a bit, was pretty much just vomiting my thoughts there but I hope you found something helpful in the post
