The best advice actually is to figure out and try it on the various classes. That's the fun and also painful part, especially when you thought it would work but you get tooled.
(please don't flame, I'm not saying I aren't going to provide him some tips)
In my opinion, druids aren't so powerful. Yes, they can hunt a foe down fast with pathfinding and condor. Unless you are relatively new, it is easy to escape him. Druids need preps and this comes basically from herbal forage. Depending on the course of action (eg raiding), you might want protective herbs.
Nearly every class can kill a druid. As Kiraan, fighting Kostyan (sp?) was a pain. He was not yet Emperor then and his crushing blows pwned me many times. Then I have this village commander, er forgot his name (svirf), his pincers hurt bad. Good thing Iltch was on my side as Nexan. I'd hate to get jacked and trussed up and dragged away from my COW, treant.
-What would be the first level you would say a wood elf could comfortably sit at to start pking?
Once you have an offensive spell. Earthquake is a bit of a mixed blessing. But if you have a tank, you can spam earthquake to kill your victims group. Also if you lead, you can walk very fast when they run away while your offensive tanker spam bash/trip, etc
With treant, you can get him to rescue you. For that level, the treant still does a fair bit of damage. But those iron vulnerability hurts especially when they can pin you down, eg pincer.
-How hard is transmute to metal to perfect if I REALLY concentrated on it? Has anyone ever took the "never blow up objects" edge yet?
Don't think that edge is worthwhile to take, unless you know where all the shinies are and don't want them to blow up in your face. Concentrated on it? I never knew you could concentrate on it.
Tip: Getting the right herbs will give you 1 hour duration to transmute another item. If not, it could last 10+hours (can't remember).
-Weapon damage seems neglegible... would it be better to find nodrop maces or use exotics instead of just anything.. to keep parry?
I tend towards a supp-user than weapon offensive. Exotics are really really nice as another offensive action, especially when you are indoors, out of wilds area, instead of just fireseed which has a random hit.
-Do your sups take a large hit outside of wilderness? Are druids affected that much by fighting in a city let's say like a ranger would?
I would think so. They are afterall 'forest priest'. I played a Nexan, so I wasn't always a treehugger.
-I rarely see heros using fireseeds... and I don't want to be a cookie cutter druid with sunray sunray sunray... at hero.. what do thorns do on average for damage?
Er, cookie cutter? Sunray is really cool, and when you take the sunray edge, it's even better. But then you are limited to outdoors and daytime. Hurts orcs, duergars. Thorns does ANNIL and OBLIT damages (herbs play a large part too) but I think thorns is physical damage. So giant resist, etc might be a factor here.
Fireseeds are not dependable that's why heroes rarely use them unless necessary. Also if you are not tanking and indoors, consider using the bearform. Does better damage than just fireseeds.
$0.02.