Primers of all sorts are fine over shackle. The most commonly used and available is latex primer.
Etch primer
Start with a primer, Perma Seal is great. then I would use oil based paint.
You should always use primer first.
Spackle is actually a trade marked name. Although it is used to describe the gypsum and glue mixture in a generic way, the name actually belongs to the Muralo Company. It was so successful, that the name is now used to describe the gypsum and glue mix no matter who makes it. Spackle is called Polyfilla in Commonwealth countries. Again Polyfilla is a trade name, but like Spackle, is used to describe the product regardless of the brand. The Spackle brand was launched in 1927. The original trademark patent is still on record with the US government. In the trademark application it is described as a: SURFACING COMPOUND FOR FILLING IMPERFECTIONS SO AS TO BRING UP TO A SMOOTH AND LEVEL SURFACE AREAS THAT ARE TO BE PAINTED OR DECORATED. However, the mixture was already used prior to this. What Spackle did was simply supply builders with a ready made product. References to the gypsum (or plaster of paris) and water mixture predate 1927. It's been around for a long time. One of the more peculiar patent applications using the name Spackle was an abandoned patent for Butt Spackle. The name Spackle has become part of the American language and has become synonymous with crack filler. The Butt Spackle didn't use real Spackle, but was a "novelty gift in the nature of containers filled with a dough-like material". It would be interesting to know what the owners of the Spackle brand thought of this use of their trademarked name.
Remove all the loose flakes with a scraper or putty knife.use a spackle to fill in the gaps in the surface.Sand the surface to smooth and hit it with a coat of primer paint.
To fix a ceiling that was spackled with drywall mud instead of spackle you can use sand paper to scrub it. I don't understand why you have a problem with it. That's quite common. you normally just paint primer over it. Using sand paper to scrub it is going to be extremely dusty.
Depending on what type of spackle you are using and how thick it was applied it may need to dry longer, but you also need to prime the spackled area before painting. My experience has been to use an oil base primer and any type of paint can be used over it, oil primer works well for a bathroom.
Etch primer
NO ! - woodstain does not use a primer.
Use Kilz Original, it's the best primer.
Start with a primer, Perma Seal is great. then I would use oil based paint.
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.
No you can not use primer as your paint because it has no sealing properites in it.
You should always use primer first.
Regular drywall primer.
Spackle is actually a trade marked name. Although it is used to describe the gypsum and glue mixture in a generic way, the name actually belongs to the Muralo Company. It was so successful, that the name is now used to describe the gypsum and glue mix no matter who makes it. Spackle is called Polyfilla in Commonwealth countries. Again Polyfilla is a trade name, but like Spackle, is used to describe the product regardless of the brand. The Spackle brand was launched in 1927. The original trademark patent is still on record with the US government. In the trademark application it is described as a: SURFACING COMPOUND FOR FILLING IMPERFECTIONS SO AS TO BRING UP TO A SMOOTH AND LEVEL SURFACE AREAS THAT ARE TO BE PAINTED OR DECORATED. However, the mixture was already used prior to this. What Spackle did was simply supply builders with a ready made product. References to the gypsum (or plaster of paris) and water mixture predate 1927. It's been around for a long time. One of the more peculiar patent applications using the name Spackle was an abandoned patent for Butt Spackle. The name Spackle has become part of the American language and has become synonymous with crack filler. The Butt Spackle didn't use real Spackle, but was a "novelty gift in the nature of containers filled with a dough-like material". It would be interesting to know what the owners of the Spackle brand thought of this use of their trademarked name.
a primer is liquid you apply before painting , to help the paint stick to the surface that you are planning to paint.