Accounting system of some sort (Quickbooks), and then your biggest challenge will just be marketing and getting customers. 

My guess with all the back and forth something was missed and you could claim there is no contract.

Now I do advise my customers to insure the full replacement value so that if a fire or anything else does wipe out the house you can actually rebuild it, but its up to you whether you want coverage to rebuild or just enough coverage to protect what you bought it for. 

Get the party that wants to sell to assign to you his/her right to collect all expenses that the deadbeat co-owner has not paid (an Assignment is a simple one page document) and have the seller sign a Quit Claim Deed granting his/her interest to yourself or to another investor. 

@Steve S. you'll find a lot of tenants claim they can't even afford $10 but they're just looking to see what they can get away with.

Buy a unit that you / your manager can deal with the typical customers who will rent those units. 

I see them all the time on ConnectedInvestors but just make sure to do thorough research on these investors and their claims because that site is more spammy than BiggerPockets.

Looking at the info, this is what the software claims to provide.

Have you tried filing a claim against their insurance first?

From a local bank's latest 10K: "Substantially all of our loans are to customers located in the immediate market areas of our banking locations …" I'm seeing more of this type stance lately and I don't think it's me.