Absolutely. It takes some guts to throw them the first couple of times, after that you get the feeling of that rotation. It's helping to build my confidence to try them on the water.
No idea but I'll start looking for her. Oh and by the way, make sure you use a rope when trying your off axis spins. I have not ever tried without it although its probably posible.
O/A's without the rope are possible...they just turn into a half corked/half backside rodeo (snowboard lingo)
When doing them with the handle think about to things 1) try to pass the handle under your butt rather than in the small of your back 2) think about throwing your feet up and back while rotating frontside (or backside if you're more comfortable that way)
O/A spins on the tramp are actually quicker rotation. For example, I can do an off axis 720 but I cant do a regular 720. Also, certain tricks are easier switch on the trampoline.