The Colt 1911 A1 is rated at 395 FPS (Feet Per Second)
Colt makes a 1911-A1 Pellet gun made by Umarex. I know of no BB gun unless you are asking about an Air Soft gun. The Pellet gun is very good. I can not answer about an Air soft gun.
If this is an Airsoft gun then 6MM BB's should fit.
The Colt 25 airsoft BB gun cost between $10 - $15 depending on the model.
About 100yd
It's probably an abbreviation for meters per second, the velocity of the BB.
Colt makes several different models. Which one are you asking about?
Colt has 5 different model Air guns. The Defender is the only BB gun, the rest are pellet guns. Umarex makes all the airguns for colt. I suggest you contact UmarexUSA and ask them for assistance or repairs
You don't. It strictly a BB gun. It is not designed for Pellets.
See the link below for the owners manual.
I suggest the you contact an air gun repair shop to have it fixed. Try looking up "Air gun repair" on the web and have them repair it for you.
It looks like an old Colt 45. See the link below.
If its a BB Gun, Then Yes.