New galvanized what ? -Are you talking about galv steel framing ? If so it need no priming. Steel studs are within the wall and do not need any kind of primer or paint.
Depends on the water quality and what type of galvanized piping was used
Metal LENOX
"Drywall primer" -Yes, -it's called exactly that -right on the can !
percussion
No. Galvanized pipe is what they used to use, and now should either be replaced with modern type of water pipe such as PEX or copper. COMMENT: Complete agreement. Galvanized served it's purpose and did bring water into a lot of people's homes for a lot of years. That was then, this is now. Today, it would be a dead last choice for a plumbing system.
As long as the surface is clean and dull, then either an oil or acrylic primer can be used to cover oil-based paints.
1 1/2"-2 1/2" 8d galvanized finish nail. length depends on thickness of item you're securing
Pvc, Wirsbo, Copper, galvenized, pex, or Polyethylene
Drywall primer should be used.
I would sand it down with sand paper then paint with primer. After that apply a outdoor paint. Prep work should be smooth If you really want it to be nice hit the primer with a light sandpaper after the primer coat.
If the primer was a water based primer, then you are in trouble. If it was, then you need to strip it down to the metal and use either an oil based primer or I would use a primer made by Rustoleum.
zinc