Greetings and Salutations, I'm building my first upper from scratch and could use all of the tips I can get.

I figured I can just use any mil spec upper, or does it have to be a dedicated AR9 upper?

To my understanding you just need the hand guard/barrel nut to be torqued to secure the barrel itself or is that wrong?

What ounce buffer is recommended for smoother recoil? I know it's a straight blowback design so anything to aid in better control would be appreciated.

I already have a dedicated ar9 lower that is glock mag fed. Do I need an upper with specific feed ramps or something?

The mag release that came with the lower is a cheap feeling plastic, is there any recommendations for an upgrade?

Thank you, I appreciate any help, and as always have a nice day.

http://imgur.com/a/dmBOv11