No, Christy's Red Hot Blue Glue is a very fast setting PVC pipe cement. It does not need a primer unless local codes require.
No, Red Hot Blue Glue works as a solvent cement for PVC material. It will not solvent weld polypropylene material.
I have not attempted this procedure. I don't believe it will work. What I suggest is finding a pvc piece with threads that screws into the brass on one side, with the other side glued to the pvc pipe. I hope that you find this useful.
Yes it does.
Plexiglass is a different chemical formulation that PVC pipe. Solvent cement for PVC pipe will not bond the two together.