"What Pontiac did you buy, and what is the LS4 engine, in non-GM people's terms? V8? V6? OHV/OHC/DOHC?"
A Grand Prix. The LS4 is a 303HP 325 cid V8. It has displacement on demand so that at highway speeds it operates as a V4 for some, but not significant, fuel savings.
Sounds nice, they're not a bad looking car at all, and that front-drive V8 platform is pretty decent - a little heavy at the front and prone to torque steer, but what high-powered front-drive car isn't? I hope you have as good of luck with it as you expect, from your previous experiences.