Don't paint it when your weather is very hot or very windy. The paint will crack or blister. The wind could blow dust or smething else onto the paint. You can stain it any time. I probably wouldn't stain it if the weather forecast says it will rain tomorrow. Whichever method you select, make sure the deck is clean and dust-free.
No, you need to remove the paint first.
can you stain over kool deck pool paint
You can try paint remover or paint the desk color over it.
You should never paint a deck, the paint will peel (unless you live in a very arid climate I guess. The deck may be stained, you can put either oil or latex stain over old oil stain.
Yes solid color stain
No, you should not apply urethane over deck stain. You should sand down the old deck stain first before applying any other type of finish.
Yes.
If you paint over the "weathered" paint, it will chip and cause the stain to come off. Also, the stain needs a clean sanded surface in order for the wood to absorb it. Otherwise, there is no reason to use stain.
Use the thinner of that paint and hope it doesn't affect the stain. There is no other way.
Yes you can.
Can you put stain in polyurethane to darken the color?
Get a new dry wall or paint over it. The stain stainsthe wall, so you can pretty much only paint over it.
You can use a 100% acrylic solid stain on a vinyl deck without using a primer. It will be opaque, like a paint, but will not mask the texture that gives the appearance of wood.