I have XP-64bit professional, and am looking to upgrade to Windows 7. Amazon has the "Microsoft Windows 7 Home Premium Upgrade" at $90. I need to bite the bullet and do the upgrade, and this options looks $80 cheaper than buying outright a stand alone version of Windows 7 Premium.
1. Windows 7 upgrade is meant only as a Vista upgrade, if you're running XP you'll have to do a clean install. But yes it should "work".
2.There is no specific Windows 7 version to get when moving away from another OS. There three different types, Retail, Upgrade and OEM/System Builder all with different pros and cons, but are the same OS. But as i mentioned upgrade will work fine for you, you will just have to do a clean install.
I always recommend clean installs anyways. From my experience it's never a good idea to upgrade from one Windows version to another because it migrates the old registry into the new one and things are likely to become sluggish and more chances to get weird bugs afterwards, etc...