Extruded aluminum
No this kit only comes with the items pictured: Buffer tube, buffer, and spring.
The Tacfire A2 Style Buffer Tube, w/Spring and Buffer will work for a 300 Blackout pistol build. However, this kit includes an A2 buffer tube which would require A2 specific stocks and braces. Also, some tuning may be required by using different weight buffers in order to achieve proper functionality and reliability.
As long as it is a fixed stock, yes it should work.
One is made for an AR-15, the other is for an AR-10.
You could replace the buffer tube that's on the grip assembly, but it will not function with the stock. You would need a fixed stock instead. You also would have no need for the spring or buffer.
No it will not.
Both versions consist of the buffer tube (also called receiver extension), spring, and buffer.
Yes, this should be compatible.
The AR-15 model has a net weight (with spring and buffer) of 11.9oz. The AR-10 model has a net weight of 11.4oz.