1) Pinkies/fuzzies (mice) are way too small IMO for even babies. But besides that point, I go by the 10-15% rule. I weigh my snakes once a month and take their weight and times it by 10-15% and find a prey item that fits: sometimes I pick some that are a little smaller or larger depending on the snake (one of my BPs will only take smaller prey, for example)
2) All my tubs are set up pretty simple: two hides (or the younger ones), water bowl, thermometer/humidity guage, and maybe some fake plants or "driftwood" in there for hiding purposes. My corn's 20L tank is very realistic/natural set up since it's more for a display cage.
3) Almost all of my snakes were shipped, and some breeders ship yearround, some wait till the temps are in certain ranges (I usually see in between 40-90 degrees they'll ship or offer a live arrival guarentee).
4) I handle my snakes mostly to clean tubs, weights, or to take photos: I like to give them their "space" so they don't get too stressed. The amount of handling depends on the snake I think: some tolerate more, some less. You'll just need to guage your new snake and learn its personality to see how it reacts to different levels of handling.
Also, I would check to make sure snakes are allowed in your dorm before jumping in and getting one.
Welcome to BP!