Upgrade to new iMac

Hi I have just bought a new imac and cannot migrate Parallels 6 to it (I believe Parallels 6 won't work with Mountain Lion?)
So I'm thinking of buying an upgrade to Parallels 8 (just been sent an email offering me this at a good price)
If I buy the upgrade, if I cannot load Parallels 6 onto my new imac, will the upgrade work?
Also can I get the upgrade as a download as there is no CD/DVD drive on new iMac?