trent, i am not sure why the bike would be stuck in gear. more than likely you are going to open it up and take a look at the clutch. its just one cover, but its a wet clutch so get a bucket.
yes the battery is for the lights and stuff. it acts as a voltage regulator as well.
it may not need a rebuld, who knows? my 56 year old c50 started by adjusting the timing chain. It seemed like the dude before me over heated it and had a soft seize due to a hole in the exhaust. when the piston seized the timing chain moved on the sprocket one tooth. i had to take the top end off, resent the timing chain and then put it back together. i still have to weld the exhaust though. ill get on it soon. haha