Follow the guide in my signature. You're putting way too much into this, it is not this complicated.
Edit: Additionally, unless you have a OEM computer your product key is NOT on stored on the UEFI. The OS itself DOES NOT put it there, it is put there by default from the manufacture. Thus, if you bought a stand alone motherboard (or a non-OS OEM system) it does not, and will never, have a Windows product key engraved in the UEFI. What does happen though is it will connect to the internet (Microsoft's activation service) and it will tie your activation with your motherboards unique identifier. So when their activation service wants to verify if you're trying to use the same key in 2 different systems it can say "Oh these are 2 totally different machines and we're not going to license you for the second machine until you unlicensed the first."
IF YOU HAVE ADDITIONAL QUESTIONS please ask me only after you have read my guide in its entirety. Thanks.