1. You could swap cables and jumpers back and forth or buy a devise made by Trios to switch drives.
2. It depends on how you hook them up, but if you wanna transfer files I would use fat32.
3. Yes you would just be swapping the Hard Drive.
4. No because you would need another license anyways.
5. No because if you had them on 2 drives the other wouldnt know the other existed.
I would recommend that you put both operating systems on the 13Gig, dual booting them and use the 40 gig for storage. That way you always have access to everything.