I have no experience with betas myself but based on what I've read, it's best to partition your drive and install Yosemite on a separate partition than your productivity system, on another Mac that isn't crucial, or on a bootable external hard drive.
It's a beta so it will have bugs.
Well, you could clone your existing partition to a new one using an app like Super Duper and then upgrade that to Yosemite, in theory it would work. That's what I'm going to do...
What Super Duper does is create a bootable backup of your system to another hard drive/partition. So you could boot from the backup and upgrade it to Yosemite.
I have no idea how to disable emails, lol I just joined today...