That would depend on the temperature "Temperature pressure relationship" and the fittings used
Yes.
no
Nope, it can be brazed, soldered, threaded
What does the schedule have to do with the material as schedule is the wall thickness Schedule 10, 20, 40 80 and 120 (XXH) The Schedule is telling you the wall (INTERNAL) thickness 10, 20 40, 80 and 120 XXH Whether it be steel, brass, galvanized and wrought ` About the pressure capacity, it is not the same because every material such as steel, brass, galvanized or wrought has a different strenght of materials.
Any Spyder threaded barrels.
A typical brass screw is a threaded rod with a head. It is not a slot at all.
Yes you can do brass low and high pressure die castings.
Yes, you can either solder them or fit mechanical (threaded) fittings.
Any pipe dope will work but Teflon tape is a lot cleaner.
Left and right nipple and coupling / union / TP coupling
You can put an aerator wherever there is threading for one.--I'm not sure of your description "brass faucet valve". - The end of the spout is generally threaded for an aerator.
Yes, the shower neck is threaded into a brass fitting nailed to a wall stud.