a. it requires a consumer, "boxed", retail package.
b. The OEM Windows has never worked that way.
Leeshor --
a. No, not really. I also bought a lot of keys online from MS directly (both Win7 & 8) with no software delivery involved, and there was no requirement to specify 32 or 64. The key didn't care. Then, as I moved away from 32-bit, I would do a clean install of 64-bit on the same machine, and use the same key previously used with 32-bit, with no validation problems. That is when I figured out, as you reported, that MS was tracking a "hardware signature" for activation.
As I replaced machines with newer and better stuff, I would have to go thru an "extended validation process," but that was clearly because I had changed the hardware signature. I would occasionally have two substantially identical machines -- motherboard, video card, etc. -- and I found that I could move a drive from one to the other without problem as long as I wasn't running the same key on two different, although identical, machines at the same time. It was a "learn as you go" process.
I don't know if my recent problem with my office computer is a 32/64 issue or not. I'll find out next time I boot Win10 on that machine. I have some unused Win8 & 8.1 keys, so I will try one of those. I'll let you know if it works.
b. I dunno; never been one. I just take the term "avid hobbyist" to a whole new level, as I continue to upgrade my own collection and deal out the abandoned ones to local youth organizations, or similar
Take care,
Russ