That would be hard unless you use an air compressor.
Your question is a oxymoron. Pneumatic BB guns are single shot. Machine guns are Multi shot. There are several C02 driven BB machine guns
it all depends on the make and model. You did not say what kind of BB gun.
Yes I can
Pretty much outside the scope of a hobbyist
Anywhere from $50-$250
You need to Identify the make and model of the BB gun in order to get an answer not the serial number
Any gun can just as easily hurt its owner as anyone else. There are many companies who make BB guns that will last for years
If its a BB Gun, Then Yes.
A BB gun is an Air Gun. Now if you are asking is a BB gun better than an "Air Soft" gun that is different. As for better, well it all depends on what you want it for. A BB gun will do more damage than an Air Soft gun. But that doesn't make it better. basically an air gun has hollow pellets to a bb gun a bb gun has metal balls so they are basically the same gun but with different types of bullets
A "Round" is usually how many shots are in the loading chamber. it can be one or many. A BB gun can carry 100 ROUNDS but only fires one ROUND at a time. A Machine gun fires many rounds in a "burst".
Follow the maker's instructions on cleaning and lubricating your BB gun, and you will get the most that it was designed to do. If you start changing things in your BB gun, it will put more stress on parts than they were designed to take, and you will break it.
It is not possible.