Welcome Shimmix.

It is good to have a bit of adjustment both ways at the bridge. For the bridge on a PB I'd probably set the scale length with the bridge pieces 3/4 of the way to the front. You are more likely to need to pull the bridge pieces back when setting the intonation, but occasionally you will need to move them forward a little bit.

I usually drill all the holes first, but that is for staining. If you are spraying and are going to be wet sanding, our resident experts advise against drilling first to avoid water getting into the wood and causing swelling.