I use Rustoleum 2X for the base coat, (Krylon just plain sucks) I put it down good and heavy in one spraying, this way you can hide any minor scratches in the PVC AND it seems to give it a shinier appearance to the paint. I clean the PVC first with Windex and make sure it is good and dry. Any dust or dirt you get in the painting process will pick off when you peel the Oramask off. I wait a minimum of 24hrs before applying the Oramask and after I get get it on I rub it in with an old credit card to get it secured good and all the air bubbles out.
DO NOT use and up cut bit it will pull up the edges and embed plastic into it.
I prefer to to brush it in as the PVC seems to absorb the paint a bit or it just needs to get it into the texture created by the bits. Trying to rattle can it you have to put way to much paint down to get good coverage and I have had it peel up the Oramask as it dries along the edges.
I have had bleed through on several wood projects So I am still working at that.
I think I have covered all the questions if I missed something just ask I will respond. Steve