[thristian]

0: Empact lists a few here: http://news.ycombinator.com/item?id=1547192

1: There are a number of highly trusted PostgreSQL consulting firms; the last time my employer needed a consultant, we hired one from Fujitsu's dedicated PostgreSQL team.

2: So far, I've only needed the (deliciously comprehensive) PostgreSQL online docs and (sometimes) Google; most Google searches wind up on the official user/developer mailing-lists, so that would be another good place to ask.