IIRC, if you run 15" rims, you'll have to make sure that you have enough offset to clear suspension or brake calipers (can't remember which).

I'm running 15" rims but have a lot of offset which causes it's own problem with interference. I get rubbing at full lock when the outboard edge of tire contacts the inside of the fender well.

The VX is pretty capable stock. I don't think that I'd mess with the e-brake to make the LSD in the rear work better. It already does a pretty good job. Some have installed a locker up front tho to add traction.