The biggest issue is the air handler....

From some other advice I have received, one of my biggest costs would be installing fire walls between the units.

This agreement will contemplate spell out solutions and procedures for for all of your questions above including how to split monies and profits.The biggest thing to remember is a true partnership is like a marriage.

You'll be shocked at the difference in taxes in the southern states and what that does for your cash flow on rentals, though.From a math perspective, the biggest advantage of real estate over other investments is leverage, especially when the rates are as low as they are. 

Today, their biggest export is emigrants trying to escape.

My biggest problem is with the people who want to do it.

Guy is one of the biggest crooks out there.

BUT, I believe a fly in the ointment could be "them remaining the PM", which doesn't seem like a good idea to me.Finding a good Property Manager is perhaps THE biggest hurdle in keeping the expenses of owning property down to optimum.

The biggest issue you need to address is a finding a bank that does business in both places.  

One of my biggest take aways was the value of knowledge, planning, and running the numbers.