meh people do them different ways, usually i fs switchup pretty fast after getting on so i dont like jumping on completely 90 or past 90, i find it easier to hop to fs when your momentum hasnt carried you yet to bs.
and for the 720, just do it off a like 20 ft table. crank that soldier boy n spin it. how many days do you really have a powder day you know? I would always say that... o ill just learn that trick into powder but i have never once went up and built a booter to learn tricks. you just gotta do your best to throw down in the park and only do tricks when you are pretty confident with yourself. If you don't have confidence in yourself when trying a trick then don't try it yet. Just do more 5's until your super comfortable with spinning. btw spins, especially off small jumps are pretty hard to hurt yourself on so you shouldnt be too worried. I'll bet you'll try a 7 get pretty close and fall because you didnt completely commit, then once you fall you'll be like fuck that could have been so easy, you'll try it again and then you'll stomp the shit out of it the second time and wonder why you've been so worried about it. anywho have fun peace.