Yes, you can,
You can use either oil or water based primer as neither will affect the flammability rating of the surface once the coating is dried.
Yes you can. You can use either oil based or a water based. I prefer a water based myself.
Yes.
can i use water base paint over oil base paint
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.
Not a good idea, better to use oil based primer.
Yes. Clean and degloss the oil based paint, apply an oil based primer, then apply the water based paint.
You can use either a water or oil-based paint over a latex primer.
Yes, you can.
It depends on the wallpaper. If it's paintable, then the water based primer will adhere. In fact, a latex paint will adhere without a primer. If the wallpaper has an anti-stick coating on it, then it probably isn't paintable.
Start with a primer, Perma Seal is great. then I would use oil based paint.