Everything stock from 2.2.1 is (should be) available on beta 2. You may find some apps don't perform how they should as 3.0 is still a beta. Jailbreaking is still an option but honestly, what is the point? You have a lot of features with stock 3.0 and as its a beta you will have to re-jailbreak (if possible) when a new beta is released, every couple of weeks or so!?
Its available that way, but you need to make sure you are registered as a developer. And I definitely wouldn't recommend jailbreaking it, nothing works, and like Croucher said, 3.0 covers most of the better points of jailbreaking anyhow