My understanding is that only the Zero S and DS qualify for the California rebate. I think the rebate is geared toward rewarding street riding/driving and not off-road "recreation" riding.
As to your other questions, I don't think there is enough information out there regarding the future Brammo products. When they come out, my guess is that they will be superior in performance to the current Zero models, but Brammo has not announced the final specifications for the models, nor when they will be available for purchase.
In my case, I figured that a bird in the hand was worth two in the bush and bought the Zero. I just didn't want to wait.
I think if you can wait for a new EV of any type, you will always get a better product, due to the rapidly advancing technology. But if you keep waiting for the next greatest thing to come along, you might never end up buying anything. Eventually, you have pull the trigger and only you can make that decision.
One other comment that might interest you: I just mailed in my CA rebate application and noticed in the application that you are signing a contract verifying that you agree not to sell your EV for a period of 3 years. If you do, you may have to return the rebate. The rebaters will be watching your DMV vehicle ownership records each year to make sure that you still own the bike/car. Something more to think about.
As I was typing this, the news on my radio was reporting that gas prices could reach $5 a gallon this summer in the SF Bay Area.