Man, that's complicated. I feel like there's a lot of information missing, especially about how you came to this pass and what led to the separation in the first place.
I'm no expert, but I'll offer you this: your question 3 sounds like a way to use his parents' interests to get what you want, i.e. to continue to live together. I don't suggest that! You're better off actually detaching than making up reasons not to do it, I would think. If you tell him you're living together in order to "give his parents hope," I put myself in his shoes and it just sounds like you're suggesting I live with you so that you and I can fool my parents into taking on a white elephant of a house. I don't have any way of knowing whether that's a fair assessment, I'm just telling you the impression that it makes.
If you want to live together that badly, I would think you'd be better off telling him honestly that you don't want to separate, but being prepared for him to say "Sorry, that's the way it is." Detaching is about not pursuing and not being needy, so if you can't avoid suggesting that you stay together, be sure you avoid begging him to stay or repeatedly asking after he tells you firmly that he needs the separation.
Now, one of the experts may come along and tell you that this is all wrong, and if they do, you should listen. I've never been through a separation or a walk-away spouse. But that's my two cents, worth what you paid for it.
