Interesting... I could never do them on the trampoline but there was a time that I could do em huge on snow.
Jumps: first get comfortable doing lincoln loop to 180 out, then for the flatspin you basically want to do the same trick except not go inverted. To do so, I would lean back onto my tails riding up the ramp, I would neglect to pop off the lip, so I always took a little more speed into the jump for the flatspin. So yea, lean back, don't pop, throw a lincoln loop but try to throw it on a more horizontal plane rather than a vertical plane. The landing kind of comes into vision pretty late compared to other tricks, so have some faith and hope for the best
alley oops in the pipe: This is hard to explain, the main thing to remember is to initiate the flip by bringing your knees into your chest rather than popping hard and using your shoulder to start the flip like you would off of a jump, as this will lead to certain painful death. Flatspins in the pipe are super easy once you figure this out.