Fenris,
I'm not sure what you mean about collecting your practice money, but if you have the game on many devices, but all tied into the same account, you can use either one of them.
As to the 5/6/7 times, and you get hit once and dead, we've all been there. First of all, ALL planes will take four hits to bring down, if you get more than that before you see them go down, it's because of server lag. Then for use to only get one hit and you go down, it can be that you only hear one hit, but you had 3 other wing hits, or sometimes when you spawn you may hear a hit or two, then that leaves you with only one more shot until you're dead, again it's a lag issue.
Don't worry, just keep playing, upgrading your planes, and you'll get better. Trust me, and ask people like Horriblebreast about how I was a noob and kept asking him questions, and complaining about having a bent barrel on my plane, the ground crew loading me up with blanks, and flying in a magnetic plane with a big bulls eye on the side.