Any FFL dealer who possesses the Class III Special Occupational Tax stamp in order to be able to deal in NFA regulated items. They'll guide you through the NFA permit process. This is, of course, dependent on you living in a state which will approve NFA permits.
If suppressors for real guns are then most likely. since they're illegal in the US I'm guessing they are in Canada as well
Do a web search on "firearms suppressors"
No. Only made for the Ruger 10-22.
No, you are not allowed to use suppressors in New Zealand
You can purchase silencers or SUPPRESSORS in attachments after selecting the gun I believe it is 2000 CoD points
Yes. You have to go through the standard federal process for suppressors.
Surge suppressors do work for your residence. They protect your GFIs and appliances. www.geindustrial.com
Yes you can. My stepfather has bought 3 over the years and I'm going to pick mine up today.
Try AR15.com Try AR15.com
Suppressors can be mounted to the HK416.
You buy them from a gun dealer. In the US, that is a dealer with a special license. You would need to apply to the BATFE for transfer of the suppressor to you, and pay a $200 transfer tax.
If it is one of the recent Colt .22LR AR15 rifles, then the answer is no - they are completely different internally.