Meanwhile, i have buyers who want to close and have extended for a few weeks waiting for me to work out this problem.Meanwhile my lender is dragging his heels along with what appears to be fully confused on what to do.   

In addition to gutter cleaning, regular roof maintenance (hopefully on a roof that isn't flat), HVAC, and boiler maintenance will help extend their usable life.

You are no longer in the deal and you did not extend seller financing to the buyer.  

50% of the unpaid balance can be had with performing firsts, if this is non-performing it's not as attractive but without details I can't say avoid it either.Reinstating a mortgage comes under the same rules as making a new loan, that is what you would be doing, you're extending credit and that may require a mortgage originator/attorney.

Well I suppose you could go on an extended vacation and still consider it your primary but you shouldn't change your address until after a year

You don't want to over extend yourself on minimally financed houses, then you will be stuck with a much higher burden if things go sour.

Is there back up for this number that is verified over an extended period of time?

I look for people matching one of three conditions: they own their own businesses, they have been members of the community for an extended period of time, or they are involved in real estate in some fashion.

:Obviously Laval has changed since I lived in the area ;-) Yeah, since the metro system was extended from Montreal our property prices have almost doubled.

I recall reading a few blog posts by startup founders funding their companies though AirBnB, but there are more efficient ways of extending your runway than subletting on AirBnB.