I feed my bp fuzzies, and people keep telling me they are too small, I should switch to 'hoppers." What size are these? Are hoppers adult mice?

Its hard to say with out a picture hoppers are pretty small. mice dont get very big in the first place.
http://www.rodentpro.com/popup_size.asp?img=size_m_hoppers.jpg&len=1.50 - 2.00&wt=8.00 - 12.00 here is a pick of a hopper

Your python should be eating one meal a week, and the width of the mouse should be equal to the width of the widest part of your snake. Hoppers are one size up from fuzzies, just below adult mice. If your snake looks hungry after you just fed him (looking around and moving a lot rather than just sitting around digesting) than that is a good indication that you should increase the size of his food. Don't worry about it being too big, if he can't handle it, he will just regurgitate it and you will know that it was a little too big.

Used to work at a pet store

Pinkies are newborn mice. Fuzzies are also newborn, but are starting to develop fur -- hence, "fuzzies." Hoppers are slightly larger, and starting to run around. The next size up is an adult mouse, so hoppers are kind of "teenage" mice.

pets question and answers,www.5d2d.com

Your python could probably handle an adult mouse as long as it's pre-killed or frozen/thawed.

Your snake should be eating a weekly meal about the same size around as the widest part of your snake.

Its hard to say, hoppers can referred to many animal such as rabbits or bunny and such