A question, for those in the know, regarding using Windows 7 on a second computer when "connected" to the first one.

That's a good idea, but for this it wouldn't work due to the Windows 7 product key only being used in Microsoft's records.  There's really no W7 product key on this computer due to the three successive upgrades with clean installs.  Technically the only way I could disassociate W7 from this computer is if I purchased and installed a full copy of Windows 10 on it and that W10 would stand alone.  That way the Windows 7 key this was all built on would no longer be in use.  It's kind of like Jenga.  I can't remove the bottom piece (Windows 7 product key) without having the whole thing come down.