Re: Who's gas plug and recoil buffer should I get----
I think he means "gas block" and buffer.
If that is the case, I recommend Slash's buffers. For suppressed shooting, go with the XH buffer (carbine or rifle depending on your setup). See here for more details:
As for the gas block...that is your call. Paladin Machine makes an adjustable version, as does JP Enterprises. I have used the Paladin version and while it is nice...it isn't absolutely necessary. You can use the stock gas block that came with your rifle if you like.
One other thing I would suggest is a PRI GasBuster charging handle. Its that or break out the RTV and get cracking. I run the GB CHs in all my ARs that I shoot suppressed and they work exceptionally well.