Unlocking 550 BE with Biostar TA790GXE questions

I just bought a Phenom II 550 BE along with a Biostar TA790GXE mobo. I have been toying with the idea of trying to unlock the CPU and had a couple of questions:

1. Can this mobo be used to unlock it? Looking at www.overclock.net it appears to be the case but they don't list what BIOS is needed.
2. When I unlock it is there some way to control whether I get 3 or 4 processors or does it always unlock to 4?
3. Most importantly, if the unlocked version appears to be unstable, can I reset this mobo to get back to the original dual processor?

Thanks.