Hi Alien
1) You can give Ubuntu the whole 102GB to start with, then use the partition tools to take 80GB back later, It's up to you though.
2) The third one is the separate 'home' partition that Cobbydaler suggested. That's not really necessary for your first try with Ubuntu. But you decide.
3) No, not 6GB for swap. That's why I said the value isn't critical. In practice you might not do any swapping at all. But if you are given a choice then plump for between 512MB and 1GB. Even if you never use it, you won't miss 1GB from a whopping big hard drive.
