I am going to research laws in Missouri, but does anyone know how I would go about refunding the already paid rent if she does leave?

Let's say I buy a multi family property using an FHA, I live in it for a year and then after 1 year has passed I decided I wanted to sell it and leave the country.

This varies by state but in one of the states where I have rentals, I believe if they vacate and leave stuff behind you can move it or store it.

Some of the "substance" can be take it or leave it, and you can potentially be a little more self-directed.  

I’ve been trying to find some 2-4 unit properties with the intention of renting out all but one unit long term, then leave one unit open for me to go back and forth from Michigan.

There is actually quite a few differences between the loans with their structure and fees but for rental income here's what you need to know:FHA loans will require there to be 25% equity in the property you are leaving in order for them to use rental income. 

Meaning you took action and bought properties, as opposed to those who just give opinion without skin in the game. 

If you leave the windows bare you'll be cheapening the look on an upper priced unit or opening yourself up to the tenant hanging cheap (paint drop-cloth quality) blinds using the same nails he would use to hang Christmas lights outside, 20 penny nails!

I’m leaving my 9 - 5 to pursue this full time, and am ready to work a second job to support the transition (in addition to tapping the savings I have set aside for the career change).

But many of them are dying and leaving the property to their siblings that don't believing in paying property taxes.