PS = power steering has no drain plug. You can suck that out with a turkey baster or some such. (Don't ever put it back in the kitchen...)
I've drained the PS fluid by disconnecting a hose to the PS cooler out front of the radiator. It's just a steel tube bent into a big hairpin that you can see thru the grille.

Auto tranny drain/fill only gets about 1/3 of the total fluid. So you drain & fill it a couple times IF it's dirty. Otherwise, you just drain/fill it every 25k miles or whatever interval you like. Pay attention to what drains out so you can decide whether it needs multiple drain/fill cycles.