1) Not great, go by bottle/pump for filling. Fill to 175 bar, no more.
2) Do not let the pressure drop much below 100bar
3) AA Fields, but I'm playing with Falcons at the moment which are a 14.43 grn pellet. Fast, flattish, but still with the surface area of a .22
4)Different guns by the same manufacturer like/dislike certain pellets
5)Dont undo the screw on the magazine as the ball bearing and spring jump out never to be seen again!
Davy will probably be on to give some advice.
Cheers
Sib