Front & rear sump just refers to where the deepest part of the pan is, the "sump," which is also where the pickup for the oil pump is. There were also some center sump pans on some mopars back in the 60's-70's. The location of the sump, as far as I know, mostly just depends on the front crossmember design of the vehicle.
Dry sump is a totally different system. A dry sump system uses an external belt-driven pump with an external reservoir. Dry sump oiling systems are used in just about every race car I can think of (nascar, nhra, etc) because they're much better as far as oil control goes, plus they have better ground clearance (although that's sort of a minor issue).
You don't really want a high volume pump if you have a stock pan, in fact most of the time a high volume pump is not necessary. Just stick with a stock volume pump. For autocrossing you just want to improve the oiling system you already have- a baffled oil pan to keep oil in the sump, windage tray and/or crank scraper, and external oil cooler are all good things to add.