1 That depends on you and your coach
2 I've never seen paper shot with a pistol using other than flat nosed pellets
3 What you pay for a second hand gun is up to you, I've seen Rohm Trainers sell for over £300
4 The better you get the better results you'll get with whatever you shoot, you should be happy with your pistol though, if you are not then you'll always be wondering if you'd have done better with a Steyr ;-)
If I were starting out in 10m I'd buy a Gamo Compact, fettle the trigger and use stick on wheel weights to get the muzzle weight right then move straight to something more interesting after a season or two,
Regards,
Nick