Hello kxracer, and welcome to Seven Forums.
Microsoft allowed being able to do a clean install with a upgrade copy of Windows 7 to allow their customers to be able to reinstall the upgrade copy of Windows 7 if neeeded without having to install say Vista first, then do a upgrade install from Vista to Windows 7. It's a real time saver for this to be allowed. The red warning box in this tutorial on the first page can give you more details about this to help more though.
The red warning box in the tutorial below can help show what editions of Vista can do a upgrade install to what editions of Windows 7. However, if you like, you will still be able to do a clean install with a upgrade copy of Windows 7 as above to not have to upgrade from Vista itself.
Upgrade Install with Windows 7
Yes, you will be able to upgrade from Windows 7 to Windows 8.
Upgrade Install from Windows 7 or Vista to Windows 8
Hope this helps,