1. We pull the headers footers stylesheet and such examples can be seen here http://www.photopost.com/action/index.php
We do not alter any type of vbulletin code so if you want to show gallery stuff on the forum you would need to install plugins code hacks or mods as they are commonly called and they can be found outside the support forums on THE MOD CORNER
2. If you want to integrate with vb
you should start there but it is possible to switch integrations with some work as vb
does have an importer to import the photopost users into vb
and there are threads here which explain how to switch integrations.