On Hoth you can also "ride" the ATST... for whatever that's worth.
As for how many characters in multiplayer? Hmm... hard to say for the xbox version. Basically all the same models/skins from JK2, plus a smattering of new ones from JA (such as the Tusken Raider) - roughly 50-60 different characters (at least double that if you count team skins).
My 24/7 dedicated Jedi Academy server: 184.108.40.206
Jedi vs. Merc, Melee enabled, voting disabled, high bandwidth Multiple OC-3 Connection
Lowered sabers required to use offensive Force powers
The expressions "LAMER" or "LAMING" are NOT recognized
All kills are considered fair & legal (including chat-kills & "saber-down" kills)
Abusive language, Complaining & Kill Trackers NOT Welcome