To give an exact answer is almost impossible because it depends on several factors. I have seen people shoot relatively accurately at 200 yards with a full size pistol. In regards to general distance, a pistol bullet can travel about a mile on average if fired up at an angle.
Depends on the caliber, barrel length, projectile weight.
No it will jam in the barrel.
The barrel may be warped. You should get a return on it if at all possible.
Yes that what it takes. It should be marked on the barrel.
The only way to find out is to shoot as many different brands and loads as you can afford.
Needs to go to a repair center
Any gun can shoot blanks. However, generally speaking, a "blank gun" such as a starters pistol, has a blocked barrel so it cannot fire a bullet...real or rubber.
A 41 magnum caliber revolver will shoot 410 gauge shotgun shells but is not recommended. The shot will lead the barrel rifling. There are also adaptors you can put in a shotgun that allow you to fire pistol/rifle ammunition.
yes it can shoot slugs
Shoot it. Get some decent factory ammo, clean the barrel VERY well, take it out to the range, and shoot it. Once you have a few hundred rounds down it, clean it. Then take it out and shoot it some more. If you're looking to break in a competition barrel, then you do it slowly. It is best done with handloads, slowly increasing to full power loads. Just don't neglect to clean the barrel VERY WELL before you put that first round downrange.
Range is dependent on several conditions. The size and weight of the BB or pellet. The power plant in the pistol. C02, Pump, Spring or PCP. The temperature, length and type of barrel, and finally wind. All of these effect the distance an air pistol can shoot. It is different for each model.
You could shoot at a pigeon with a pistol.