My experience,

Short wheelbase = tighter handling, better for smaller/tighter tracks
Long wheelbase = more stable handling, better for longer/faster tracks.
Medium wheelbase = a nice balance of the two.

I personally love the long wheelbase, I like how stable the car is and well it is planted. Our track tends to be a medium track ...it isn't too fast/isn't too tight. Many run the medium wheelbase on our track ...but I prefer the long for the more stable handling.

For bashing in a parking lot none really make a huge difference in my opinion. and i'd go w/ the body you want ...let the body dictate what wheelbase to run.