No, this upper does not include a barrel nut. Aero precision does manufacture a different model though that has an integral barrel nut for their handguard line.
Yes! Every aero upper receiver I have has T marks.
Yes, the Aero Precision AR-15 Assembled Upper Receiver has M4 feedramps.
The Cerakote finish is done to the bare aluminum receiver on the FDE model of the Aero Precision AR-15 Assembled Upper Receiver.
The Aero Precision AR-15 Assembled Upper Receiver can be used for a AR15 build in 300 Blackout. It will work with Mil-Spec components and Mil-Spec lower receiver. You will just need a 300 Blackout barrel.
Yes, the Aero Precision AR-15 Assembled Upper Receiver can be used to replace the upper receiver on a Smith and Wesson M&P 15 Sport 2.
This Aero Precision Upper may work with a 80% lower. The Aero Precision upper is designed to function with Mil-Spec Components so it should work fine with the 80% lower is completed to Mil-Spec standards. I recommend contacting Aero Precision to confirm compatibility.
Yes, this Aero Precision Upper will fit an AR15 lower from PSA.
Yes you should be able to replace the Bushmaster receiver with the Aero Precision APAR501603A AR15 UPPER BLK.