rear wheel bearings

Hi

I'm about to change my rear wheel bearings and have a couple of questions for the experts:

1) Are these a 1 or 2 piece (inner and an outer) type of bearing?
2) Do I need a press to remove them?

3) Is there an upgrade bearing that fits ? I seem to remember something about a tapered WRX roller one being used with little difficulty.

Thanks for the input!!!!

Hotshoe