Quandries in OS for new build

[hogwallow]

My existing PC has Windows 7 Home Premium, 64-bit on it. I'm building a new machine with 32GB of memory so need to upgrade and have a few questions:

1. I'm inclined to go with Windows 7 Professional 64-bit rather than Windows 8 because it's probably going to have more stable drivers across the board at this point. Is that the right thinking?

2. Can I install the new Windows 7 Professional just using the key and disk from Home Premium or do I have to install Home Premium first and then upgrade?

3. If I have to do the Home Premium install first, will the OS immediately recognize the additional memory once I perform the upgrade to Professional?

3. If I upgrade, will my existing machine's license immediately die so that I can't operate both machines for an interim period?

I'm disinclined to do the Anytime Upgrade route because with a home build I want to have the full disk handy.

Any help appreciated ...

 

[rgd1101]

1)Yes
2)Key is for the specific edition, so the key for Home Premium won't work for Pro. Need to buy a upgrade.
3)It might recognize it, but won't be able to use it.
3+)Is this a OEM copy or full retail copy. OEM can't be transfer.