From what you're describing, I'd say the rifle is almost certainly set up to shoot surplus/imported ammo. When properly set up, your rifle should eject the spent cases at least a couple of feet away. Rather than messing with the gas-system adjustment (it really is kind of a pain), I would just try to get some surplus or imported ammo if I were you (more powerful and cheaper anyway). AIM has currently got 340 rounds of 1970's production 8mm ammo for $100 and it even comes packed on stripper clips (that's how your rifle was meant to be loaded).
The only caveat to using surplus ammo is to not, under any circumstances, shoot Turkish ammo in anything but a Mauser. Turk ammo is loaded very, very hot and is known to cause problems when fired in a semi-auto. Turk ammo is brass cased with silver-colored bullets (likely either nickel or mild steel jackets) and typically comes on brass stripper clips in 70-round green cloth bandoliers. Thankfully, most of the Turk 8mm ammo dried up several years ago and you don't see much of it anymore.
Any Eastern European ammo (Romanian and Yugoslavian seem to be the most common these days) should be just fine for your rifle. Likewise any imported commercial ammo like Wolf, Prvi Partizan, Norma, or S&B should also be fine for your gun.
As far as the stock goes, I don't see any reason not to try an epoxy repair. The damage sounds like it's mainly cosmetic and you're not going to hurt the gun any worse than it already is. Personally though, I'd still be looking for a replacement stock as I prefer these rifles in their original military configuration.
As far as the "cleaning bullets," I've heard of them before but never used them myself. I wouldn't be surprised to see some minor pitting in your bore as that is fairly common with Egyptian rifles (years of shooting corrosive ammo). So long as the rifle shoots well, I wouldn't worry about what the bore looks like. Personally, I'd just clean it normally with a good copper-removing solvent.