Dave,
It's good to see this much interest, but I'm worried that you're working on stuff that doesn't necessarily need fixing! For example, the nextval stuff is fixed by some automatic filtering of SQL queries in tcl/postgres.tcl. I'm sure a couple of errors were still there, but certainly not 300....
So, we're open to having more people on the team, definitely, we're not a closed development team. I recommend you not hesitate to post more of your thoughts, so that you can get the feedback from the whole team, and we can solve these issues together! I hope we can get your help on this in the long run, this is the kind of enthusiasm we need!
Stay posted, I'm in the process of upgrading the way we do CVS and development in preparation for 4.0 development. We won't be porting 3.3, since it's more experimental than anything else.
