How much time, money, and confidence do you waste when you don't close a deal and have to start from scratch again?  

If not, what's the best way to minimize my income tax?

If the equipment is older than 10 years, I would say stop wasting money on repairs and get it replaced (you may be able to reuse the existing outside compressor it uses R410a refrigerant, but if its R22, it junk).The way they left it, it is not operational for either heat or cooling.Personally, I would review what you paid to the original HVAC company and see how they took advantage of you.

The repairs were very minimal re-painted the exterior and finished trimming and painting the inside.

I think that's the thing that I'm most apprehensive about, besides wasting my time, or getting burnt on a deal.

It’s a couple of thousands you’re going to waste.

These developers have being doing for a while so they have their system down so much so that they don’t even have to speak to their architect and waste time making decisions.

So set up a automation system (REIblackbook.com) to stay in contact with them with out you wasting to much time. 

I would appreciate any and all comments / suggestions to cut down on our portion of heating cost while minimizing the amount of work and cost to us. 

Don't waste your time with unmotivated sellers.