Oil based paint has a very hard surface which makes it difficult for water based paint to stick to properly. It should be primed first. Water based primer is fine.
To make certain the water-based primer has good tooth, be sure to lightly sand the oil-based paint and wipe it down with a tack-cloth.
yes.
yes
can i use water base paint over oil base paint
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.
You can but it wont last, you will have a bigger peeling mess.
yes
No, you can't .
That is not generally recommended.
Yes. Clean and degloss the oil based paint, apply an oil based primer, then apply the water based paint.
You just paint right over it, no special prep is necessary.
Yes, you can paint oil paint over sound water based paint easily, just be sure to degloss and clean the surface prior to painting.