I used Tung Oil (Formby's) over Min-Wax oil-based stain on an antique pie safe, a bedroom set, an unfinished rocking chair, and other items. I did all of this around 1978 when we bought our first house. All of this furniture still looks great. I plan to do the same with the finish trim wood of the house I'm currently building. Unless something has changed of which I'm unaware, this should be fine.
It depends on the stain. If it is a water base stain then no. If it is a oil or solvent base it should be fine.
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, but why waste the varnish. - (it is meant for bare wood )
Yes, make sure the stain is completely dry and you should have no difficulty.
Yes.
yes
It depends on the stain. If it is a water base stain then no. If it is a oil or solvent base it should be fine.
Yes you can if it is a solid stain. However, if you're using toners or semi-transparent stains, you'll want to remove all the water based product prior to applying the oil based stain, otherwise, it will appear blotchy if the water based stain is worn unevenly.
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.
No, oil needs to penetrate the surface and the latex stain will inhibit that penetration.
Yes, but why waste the varnish. - (it is meant for bare wood )
Yes, make sure the stain is completely dry and you should have no difficulty.
Yes.
Yes, you can
Most stains, be they latex or oil based are transparent or semi-transparent, using a primer under it would eliminate the possibility of seeing the wood beneath the stain (which is usually why stain is used).A primer is used over oil based paint when you want to switch over to use latex based paint on the same surface.
Oil stain is for bringing out the colour in wood. -If you feel it needs a latex stain, just paint it over -I don't see the point.
No because latex paint will no stick to the oil stain. unless you sand the surface first then pain it