Lisa was totally behind me so after breathing a sigh of relief I set out to make that first deal happen.

If i'm scheduled for sale and they can show they can close, i'll even postpone my sale to give them a little breathing room.

People live and breath zestimate, so unfortunately that's killing you right now.

I understand the breath and complexity of this topic.    

The only tip I would give you is to relax and take a deep breath, consult more people ( which you are doing right here on BP) and keep running the numbers.I hope it works out and am rooting for you.

Put maybe $75000 down and leave me some breathing room in case of an unforeseen circumstance?

If I had to grade it, I would say C+ area.It's not stupid to just assume the mechanical need replaced; if anything, it gives you more breathing room if you find out otherwise (unlikely on a place that's been vacant 25 years).

Though I really want to get out of my current neighborhood, since house are too close no breathing space. 

start breathing again?

The dust is highly abrasive and toxic to breath, especially if it has horsehair in it and mold.