A few years ago I got a copy of MS Project Standard 2007 from my daughter's school which I installed and activated on my new office PC when I built it, using a one time only product key (Academic Promotion).
(FYI - upon careful reading of the license I saw that the software is for a current student or teacher - or a family member of a qualifying student, which was true at the time and is still true until May of this year)

Now I am considering upgrading this PC to Windows 10 in a clean install.

My understanding is that I will lose Project 2007. I will not be able to activate it again on my "new" PC and I will have to revert back to my previous Project program or buy a new/old copy of 2007 (and factor this additional cost into my decision making).
Am I correct?

Second question: since I already have the installation media, is there a way to just pay Microsoft for a single license - new product key without having to go through the whole dance of buying another DVD?
I'm not interested in newer versions, and especially not interested in paying $25/m for Project 365.