@David Rodriguez not sure where you’re located of course consult someone with the correct knowledge do take my word for it but I think it’s just a matter of ending the month to month contract by giving the proper notice properly.

I’ll refi 30 year fixed once the proper seasoning period is met. 75% LTV of new appraised value.

@Gerardo Waisbaum There are VERY few purpose built 3 and 4 unit properties in Indianapolis proper.

Take the time to familiarize yourself with the process and deliver the proper notice so you can be up and running when the time comes 

I wonder if there's a proper way to rent out rooms or "units" without having to chop up the house and adding separate entrances and meters.

You should also check that the seller has proper chain of ownership of the mortgage.

Or do I just need to make sure that the contract is worded properly and protects my interests?

The tenancy is held until they return the premises to me and/or a properly obtained and executed writ of possession from a judge sets them out on the curb.Your state laws may vary.  

Proper slope away from a house and gutter extensions can solve about 90% of foundation issues caused by water is what I have learned from my foundation guys.

Just give proper notice and go.You have a key, right?