No, you can't .
can i use water base paint over oil base paint
Yes. Clean and degloss the oil based paint, apply an oil based primer, then apply the water based paint.
That usually works quite well.
Yes, you can, this is an excellent base for sticking to.
yes.
yes
Yes, you can
Not a good idea, better to use oil based primer.
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
Yes, you can, That's the normal way.
Yes. Clean and degloss the oil based paint, apply an oil based primer, then apply the water based paint.
Water based paint such as latex and acrylic do not adhere well to oil paint. In order to paint over oil paint you must sand the surface and prime it with a good quality oil or alcohol based primer and then top coat with a water based paint. Oil based paints will adhere well to water based paints sp it is unnecessary to prime before top coating, unless you have had to do any repairs to the surface.