Hey guys I want to know:

1. What size are the WRX sedan factory fog lights on the 02-03 model years? For example: H1, H3, H4...

2. What is the correct wattage? Does the H in the bulb type stand for a particular wattage?

3. Is it okay to use PIAA bulbs that produce higher wattages from the same originally rated, lower wattage bulb? Like are those safe and won't destroy the wiring or blow fuses, etc.?

I take it you meant replacing the bulbs in the oem fogs, not the foglight units.

(1) H3
(2a) 55W
(2b) not that I know of. There are 55W H3 bulbs, 85W, ...
(3) Depends on how much higher and how long they're left on every time. In general, the oem harness is designed for 55W, which means that any bulb with a higher wattage rating would draw more current, and possibly produce more heat than the harness could take. The reflectors may also be affected by the increased heat. If you have an extra layer of lens protection, the increase in heat combined with the reduced heat dissipation ability due to added lens layer may also crack the lens. However, I recall a member using 85W bulbs on stock harness and foglight unit, and not have a problem. I wouldn't recommend that though.