Unless you're really skinny, you'll need to have the car on stands to drain the tranny, and probably to drain and fill the rear diff. The car will need to be level for filling both the tranny and rear diff. having the car set nose-up is probably an advantage for draining the rear diff. I'm not sure how pitch will affect draining the tranny. I'm not sure where the tranny drain plug is within the sump.
Since you have an 02, you'll need some crazy big metric hex to get the tranny drain plug in and out. You'll also need the copper washer to seal the tranny back up.
You'll need a 1/2" square bit (a.k.a. the business end of a 1/2" drive breaker bar) to remove the rear diff plugs. REMOVE THE TOP (FILL) PLUG FIRST! IF YOU GET THE BOTTOM (DRAIN) PLUG OUT FIRST AND THEN CAN'T GET THE TOP ONE OUT IT REALLY SUCKS. Remove the top plug, remove the bottom plug, wait for it to stop dripping, replace the bottom plug, fill through top plug with oil until oil begins to spill back out, replace top plug.
The easiest way I've found to fill the rear diff is to buy about 3' of 1/2" ID clear tubing and a funnel that the tubing will jam up onto. Hold the tubing in the fill hole of the rear diff and have someone else pour the oil into the funnel/tube held up high.
Filling the tranny seems to best be done by removing the IC (if WRX) or air box (if RS) and then using a really damned long funnel.
Torque spec for the tranny drain plug is 51.6ftlbs. Torque spec for the rear diff plugs is 36.2ftlbs.
Capacity for the tranny is 3.7qt, capacity for the rear diff is ~0.8qt.
The shop manual calls for fluid packing on the threads of the rear diff plugs. I've never noticed that line before and I don't leak, but take that with a grain of salt.