1. How fast is super fast? 45mins to empty? 12 hours? Have you recalibrated the battery? If that batt is dying you can get another one cheap on eBay. Note there are some scenarios where having wifi on can save battery (if 3G is pulling the batt down aggressively).
2. Is it running 1.5 or 1.6 or something? That is the best you can do without rooting. Rooted G1s are running 2.2.1 at the moment, I think. Haven't seen any 2.3 for G1.
Inspire 4G, CM7.2
TMo PAYG (no data). How I use it.