My John Deere battery for my lawn tractor -- LT 133 -- is (almost) dead. Can I jump start it by using battery cables hooked up to my Ford van, or is the van battery too powerful for the Deere? I don't want to fry either or both.

You should be just fine, they are both 12vdc. Your car battery is larger and can crank more but 12v is 12 v. Connect your cables just like jumping a car. The good battery has the red/black cavbles on the terminals. The bad battery put the red on the positive terminal and ground the black cable to the frame or bare steel area of the tractor.

Yep... but do keep in mind, a drained battery puts a hurting on the stator... as the engine has to recharge it... not keep it up now..

Do I have to disconnected my battery and remove it from the mower to charge it? It's a Ferris 500 Z and I would also have to remove my hydrolic system?