Ok: 1)When doing jazz improvisations, how do you figure out what notes are best to use?

2)What can be done to reduc omthpiece pressure?Lip and mp buzzing, long notes, pencil exercises.. Anything I`m missing? What about increasing endurance? I wear myself out after not very long..

3)I`m experiencing a weird sort of "second" embouchure where i sort of pinch/curl my lips in tremendosly and when this embouchure is on the mouthpiece, only very high notes come out- such notes that I would not be able to play ordinarily with my normal embouchure. What`s going on??

1) there are about 4 notes in almost any jazz piece that keep repeating, these would be the main notes that you can play around with and it still sound good.

2) just play around on your own (dedicated) time
-play any note that YOU are comforitable with and sustain it, pulling your mouthpiece away from your mouth (not all the way) and perfect your entonation and pitch.
-get some trumpet solos from this website (or somewhere else) that push you to your limits,and get better at them, then get some more and just keep perfecting and pushing your self (make sure that your mouthpiece fits you)

3) it takes different actions to get different reactions, it will take a while to get use to it.

Hope this helps