I have had success applying both flat and gloss yellow over flat white. Not sure about stripping though, I’ve heard people talk about using oven cleaner, you might like to try this on a piece of sprue first.
I have used oven cleaner, pine-sol, break fluid(with the proper protective gear, of course), even eucaliptis oil will take paint off plastic.
I normally use break fluid for paint removal as it takes some time to work. I have never had any plastic damaged by using this method. And as a bonus, if you are re-vamping an old kit that has been assembled, the break fluid will weaken C-A glue and make it easier to take apart without breakage.
I use Castrol Super Clean to strip paint. Comes in a gallon jug from Wal Mart’s automotive section for about 5 bucks. Its powerful stuff but easier to deal with than oven cleaner. As for primer for gloss yellow, I’d go with the flat white rather than gloss, flats cover better and sand easier. If you’re using enamels, the resins in the gloss that make it glossy also make it soft and slow down the drying time.
I use fume free oven cleaner and a soft toothbrush to strip paint. Put the model in a plastic container, spray on the oven cleaner, let it sit so the cleaner can do it’s work, gently clean the kit using the toothbrush. Rinse the model, then repeat if necessary.
I found that soaking the parts in Formula 409 for a few days then scrubing them with an old tooth brush and washing them works well. It dose’nt harm the plastic , is safe and fairly cheep.