Minwax stains are made to go directly onto wood. You do not need primer, and I think it looks awful over primer.
NO ! - woodstain does not use a primer.
Latex.
I've been told the stain is better as it wont chip
you would want to use an oil based primer, like kilz. it has heavier stain blocking "technology".
Only if you put on a good primer first.
If the door has a primer or a paint on it then no. Stain needs open grain to work. Stain seeps into the pores of the wood. If there is a coating, i.e. the primer or paint, then the stain will have nowhere to go. It will just sit on top of the coating until it is wiped off or dries in ugly blotches.
Yes, you can.
NONE - just use woodstain.
you only use primer over bare wood or stains. If you have really tough stains you might need to use shellac based primer, otherwise any stain covering primer.
Kilz is an economical consumer grade stain killing primer. It is designed to be sold in home centers at a low price. For harder to cover stains, a more expensive, higher quality stain kill primer should be used.
Absolutly! You just have to check to see if the primer is first an exterior primer and if it will stick to glossy surfaces. You can lightly sand to rough up the surface or just clean the surface and apply the primer. For oil based primers I would recommend Beauti-tone's fast dry oil primer or Zinsser's oil based cover stain primer.