I have attached each my full spreadsheet where I inputted literally any information that could be found on the properties, as you can see its a lot but I am an engineer and an pragmatist.

If the post office leaves in year 4 WHO would you replace the space with and at what rent?

You'll be taking a step backwards at first, but you'll find this will change quickly into running forward.Those rentals you have now, and the CF that goes along with it, you'l replace and add more down the road...and you'll find that road should be short.

After getting a quote for the asbestos siding removal, as well as the siding replacement and repainting that is needed, I now realize I was in over my head and severely underestimated the cost to rehab a property with asbestos siding.

I can send you the name of a MEP engineer that would prob know the answer.

We didn’t kick it into higher gear until I left my job and became motivated to replace my salary.  

Left and went to College in Pennsylvania, got my degree in Electrical Engineering Technology and my MBA.

All windows need to be replaced.

If he' still looking (and $2mil in value is a lot to replace via a 1031, esp if he's looking into multiple props), then you may be able to negotiate with him so that you have a contract but don't close until a little further out, giving him a bit of extra time to get his ducks in a row. 

I managed to find a replacement (more expensive and not as nice) but my family had to spend a couple more hours in the car while I searched.I've seen a lot of posts over the years about sub-leasing without owner knowledge, renting in violation of zoning laws or HOA rules, etc.