Yes. It unscrews just like the fake suppressor on the MP5 22lr rifle.
Yes, so long as you comply with the Federal national Firearms Act, which regulates the transfer of the suppressor to you.
You get and NFA Class III permit and buy a suppressor.
Slows down gases.
Not unless the baffles are sized incorrectly, and cause the projectile to come into contact with them. A properly made suppressor won't have this problem. It is, however, possible for a suppressor to affect barrel harmonics, which can reduce the accuracy of the rifle itself.
Rifle
yes
No.... You can only hunt with 1 rifle at a time
squirrel
yes
No
It was the Commando assault rifle with Red Dot Sight and Suppressor.