The new owner just needs a Google account. You can certainly create a Gmail account beforehand if you like. He/she will have to set up a credit card for payment in the Google Play Store, etc.
You've basically got it. Don't forget personal data on the uSD card, if any. I'd just wipe it and let them start fresh.
I did basically what you're describing when handing off my 2 NCs, then running CM7.2, to my sons.
You might want to consider unregistering the NC from you B&N account. I you can do that online with any browser. Login, go to My Account. Under Digital Content, click on Manage MyNook. Hover over the NookCOLOR image and select Erase and Deregister Device.
Will follow up with that as I certainly did not want to go through the process of returning to stock and then redoing CM 10.1!
Good catch on de-registration, blue pen!
My experience with deregistering for my nieces this winter was interesting: I deregistered both NCs, then did other things for a few days, like buy throway Amex cards to register the nooks to, etc.
Sat down with 24 hours to go to re-register.
Failed - got onscreen messages on both NCs saying I had to call BN.
On a whim, reregistered mine to me, then erased and deregistered, then immediately reregistered to the new account and cc #.
Worked. Repeated the process with the other NC once I had my gf's password. Worked a second time.
I'm thinking that if you do the erasure too far ahead of the reregister you get into trouble. I'm not sure if the web interface can be used to get out of the loop at that point.