Then a coat of styrene acrylic oil-based primer.

I usually throw a nice cast iron tub in instead of a acrylic. 

My only problem is the cabinets door are acrylic and some of them are a bit yellowed.

I watched This Old House install a acrylic tub & surround, it didnt seem tricky.

They're so used to putting in acrylic and fiberglass tubs, they figure, OK, steel, how different could it be -- they're around the same price point, really, so, do you really need fender washers and why do I have to go out to the truck again?

If this is an acrylic tub, then you are going to have to remove what you did to it, sand everything down nice, use some bondo to fill it in, and then apply the topkote.  

I like DAP Alex Painter's Acrylic Latex Caulk - White which can be found at most home stores.Prime wallpaper with an OIl-based Primer, like Zinsser High Hide Cover and Sealer, or Guardz (a little goes a long way, use cheap paint roller cover that you can throw away). 

You can use acrylic, polyurethane, silicone sealants or hybirds. 

But like Insaid todays acrylic latex is sonewhat vapor permeable so should perform fine.  

An acrylic type tub and surround is about $500 in materials.