Scrub it with warm water and a sponge sander block.
Yes, you can.
Just paint it on if the latex is adhering well.
no it will not stick
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
you can paint over latex paint with latex enamel.
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.
It's primer made with a latex or acrylic base. You can use any kind of paint over this.
yes
No, it is not recommended to apply latex paint over oil-based paint without proper preparation, as the two types of paint do not adhere well to each other. It is best to either remove the oil-based paint or use a bonding primer before applying latex paint.