Do you ever 1031 exchange any of these sales or do you just pay the tax and move on? 

Another option that you have would be to 1031 exchange the funds into a larger property that you can do a similar strategy with.Finally, I would call an appraiser, but 4 units and under are still residential properties and will be valued by a comp analysis rather than the income capitalization approach used for commercial investment properties. 

Basically, Rich was offering to mentor someone in exchange for help organizing his business. 

As @Jacob Sloop mentioned above, HMLs sometimes offer extensions in exchange for a fee.

I'm very efficient with Microsoft Excel and could offer some bookkeeping or paperwork catch-up in exchange for your time, knowledge, or skin on a deal. 

normal exchange?

You will get credit on your US taxes, however, for taxes you have already paid in Mexico.You can 1031 exchange after selling as long as the property you buy is outside of the US.Don't consider this as legal advice.

In order to sell one of the units, you would either have to pay off the loan or get the lender to agree to release the deed in exchange for a partial payment of the loan.

I feel like I'm in a foreign land with no tools or compass. 

Maybe even the 1031 Exchange forum if you want to try another place.