In the US, startby finding a dealer in Class III firearms in your home state. This is a dealer with a special license to sell machineguns, suppressors, short barreled shotguns, etc. They can aid you in applying to the US BATFE for transfer of a suppressor. It will cost you $200 in transfer taxes. The suppressor is transferred from its owner to your dealer, and then to you- IF your STATE laws permit possession of suppressors.
You get and NFA Class III permit and buy a suppressor.
If you can legally own a suppressor, you can just as legally mount it on a hunting/sporting rifle - however, you can't do this when you're actually hunting with those firearms.
Yes. You must be 21 years old, not prohibited from buying an ordinary firearm. There is a process to go through to have the transfer of the suppressor approved by the Federal Govt, and payment of a one time $200 tax.
Not legally.
Some states do allow it.
Yes, so long as you comply with the Federal national Firearms Act, which regulates the transfer of the suppressor to you.
Yes. It unscrews just like the fake suppressor on the MP5 22lr rifle.
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.
No such weapon, so no. However, there there is a M16A4. It is possible, but, highly unlikely that an individual can buy one.
It really does vary as to how much a surge suppressor costs depending on where you buy it from. They usually range from $15 to $25. Here is one site you can buy them: www.tigerdirect.com/.../category_slc.asp?...Surge%20Suppressors
Go to Hoover Tactical Firearms! They have them in stock!