[X] Ask for the Mod Soul back. You'll have to sit it down and lay out some ground rules, but it can't be all bad if it was able to evade someone like Kori for a couple of hours, and kill a Hollow to boot.
[X] You'll just take whatever artificial soul Mai had wanted in the first place. Or, if Kori's out of stock with those, you'll take whatever normal artificial soul she has. Preferably in a sealed container so you know it's real.