Key is going to be fun lol the Disc is easy as you can actually get the disc image from Microsoft.
OEM Keys which are bound to the motherboard they are installed on (99 bucks) will not work if the install was from a retail disc/disc image. So depending on what you installed it from if you went out and bought a system builder license to take care of this you would still end up reinstalling.
The keys on prebuilt computers are meaningless. The activation is actually tied to the SLIC table in the bios, the key itself is not... of any use to even the system its attached to for the most part.
You can run the machine for 180 days as long as you do not try to put a key in. You put a key in you go from 30 days to like 2 or 3. But you can do a rearm 3 times before you exhaust so until you get your situation figured out, literally just sit on it.