I haven't filed a claim all these years but insurance is for the what-if and to be used for the high-ticker items, but chances of damages exceeding the 5% is low.  

@Matt Powers  Have you done any training, schooling in real estate investing? 

Look at insurance and tax costs, those two items are the biggest killer of cash flow.

At the end i will add a list of items why adding a single ADU in single family zoned areas may not be the best RE option.The most common value add is via a rehab.  

These are professionals with additional training and a stricter code of ethics.

A savings to put deposits and another account for everything elseyou don't need separate bank accounts as accounting software will classify all of those items.

I think negotiations on knocking the price down on inspection items on value add will be huge especially if its a flip like you mentioned.

Also, what others have said, the personal touches on what is in your place (e.g. providing all the essentials instead of having people buy TP, coffee, shampoo, etc.) and the quality of those items (no tattered towels, stained sheets, etc.).  

It's a long train ride.

It would cash flow nicely.One item to plan for from the beginning is the exit.