First of all, they are pretty balanced, I would just complain about the vehicle unbalancing overall ( enemy vehicle shoots a wall 5 meter next to you, you die )
Wookiee, It isn't useless, the bowcaster is great if you know how to use it. Also that class has granade launcher if you dont like the bow. Only problem I see with it is the timebomb. Yeah it might be great on Endor but useless on other maps. What I would suggest is make the timebomb stick into vehicles ( Hmmmmm Im not sure if it does that' haven't tested )
Droideka, this is what Im most concerned about. How the hell do Jedi fear droidekas if one jet or arc trooper can bust one down. I know it's all about balance, but from my part I'd like the shield be more powerful. It's still dead easy to blow one up with granade as the droideka is very slow when shooting and shielded. But then again, it totally depends if you're playing on 32 server or in a clan match of 5 vs 5. In crowded situations droideka is useless, it wont even get to roll open before it is blasted, and in one on one, well it can kill most ( excluding jet and arc trooper ). Best thing would be to make it faster when walking.
So the game is balanced for clan matches, but not that well for pubs