Those mount adapters would be for Nikons manual focus, not the AF. They are both essentially the same camera, but the 4 megapixel difference. Its just a matter of deciding which MPix you want, the 10 would be easier to deal with, easier to process, easier to work with. The 14 would give you improved resolution, but 10 certainly isn't lacking of resolution (the new 24mpix full frame sensors provide the same pixel density as the 10). You'd certainly see a major benefit with 14 for macro, but portraiture might benefit with 10, sometimes you don't want to see a persons pores and fine lines. What kind of studio lights? Continuous/strobe/bounce?

And welcome to the forums! I think you'll really like the community of photographers here, they've always been very helpful and informative for me.