Just paint it on if the latex is adhering well.
Yes, you can.
You can always paint latex ( water based )over an oil based paint as the latex just dries on the surface. However don't paint an oil based over a latex paint. Oil based paints need to absorb into the wood or other surfaces or it will just dry and flake off. For more information on the differences and when or not to use a latex or oil paint please see the following article. . http://www.ehow.com/how_4713170_between-latex-oil-base-paint.html
no
No, you either need to really rough up the oil paint with fine sand paper, or put a base coat on before you paint with your Latex paint. If you don't your Latex paint won't adhere.
yes. However, you cannot use an oil base paint over a latex primer. If you change your mind on the paint, you must strip the paint before you use an oil based paint on the primer.
Yes it can.
yes
Not directly. You will need to use a primer made to adhere to oil and will accept a latex topcoat.
yes but you cannot put latex on top of oil based surfaces You actually are NOT advised to put oil over latex surfaces, which is why you're supposed to prime will an oil-based (alkyd) primer. Latex and Polyurethane should always have a layer of oil-base beneath it.
Scrub it with warm water and a sponge sander block.
I don't believe you can put latex paint over an oil base. it will never dry and will always be tacky
Yes, after allowing a sufficient time for the base to dry.