Ask the Recorder of Deeds.I suggest you get to an attorney, do a standard lease, a separate straight option agreement, both could be assigned with owner's consent not being unreasonably withheld, get a power of attorney to do repairs or a construction contract would be better, you as a tenant probably can't pull permits.

The addition adds 1 bed, 1 bath, and a den (plan to knock a wall out to open up the living room that separates the den currently).

This way you won't be competing.You may be looking at many months with a property like this, so certainly pay a commission for broad exposure to find the right tenant.Why are you not trying to lease the home and the land separately, perhaps to a neighbor, if its farmable?

There are two separate loans closing (1st & 2nd) at the same time in one transaction (the purchase or refinance).  

They won't be collecting any rent for you unless you negotiate a contract with them separately, and will certainly charge you 10% or standard rate.

I handle all my own routine low-level maintenance and have working relationships with a local drywaller, a painter, a plumber, an electrician and an HVAC guy in case any big projects arise.For the security deposits, I set up a separate savings account at my local credit union and do the "set it and forget it" mentality.

I see that you separated the gross rent from the operating expenses.

There will be 2 separate HUD's and neither will know the amounts on the other.I would suggest calling EVERY title company in your city or surrounding cities who have done these before.

Check to make sure the stores have separate gas /water / electricity (would be hard to lease out of they dont).

I want to buy an investment property during my separation period before Divorce.