Who decides who can and who cannot have a permit?
The guys with the biggest gun, silly
Good question. I haven't tried to obtain one, but my understanding is that licensure is in stages. First, they give you a permit to buy a gun that only shoots hard rubber bullets (with gunpowder though, so still pretty dangerous). If you manage to own this for either one or two years (I forget the exact interval now) without doing something stupid, they upgrade your license to allow real bullets.
As an American who is radically against gun control, this system seems overly restrictive, but the fact of the matter is 1) as European systems go, this one is rather permissive, and 2) living here and knowing the kind of stupid stuff Russians do when insanely drunk, I guess I can see the point a little.
Oops, my info was on the right track but not quite accurate. Someone above posted some good info.