Did you follow the link properly? The 'redeem your points' link in the email should take you to your account, which should have an orange 'redeem points' button.

Right click on the icon for the base game. Go to compatibility. Tick the 'Run this program in compatibility mode for". Select XP and whatever service pack.

I had no issues installing my "XP" version of the game on Vista. I changed the compatibility in the programs properties to XP and installed the first patch. Also you don't get a download folder automatically unless you run bodyshop.