Surprisingly I think I like the SFR, (lower maintenance costs and tenant interactions per cash flow dollars).

I keep reading that it will be so hard to seperate the costs for each unit.

So, yes, you can absolutely get a traditional loan using 20% down an receive a loan with lower closing costs and a lower interest rate...or you could go the other route.Hope that makes sense how I am describing it. 

Both of my parents have helped with some projects when it comes to labor but financially is myself and the lender that has been amazing through the purchase of both properties. 

The only negatives with an assumable loan is that they take longer to close, 60-90 days generally, and you would also need to come to the table with a little cash to cover the sellers equity (if any) and some other closing costs. 

And unless they're damaging the unit, I don't think I would go so far as to evict them for not paying the deposit, it will end up costing you more.What you might be able to do (check with an attorney) is charge them a late fee for not paying the deposit.

From my experience (I could be wrong) there isn't a format but the estimate should list details like the materials to be ordered and the hours of labor needed for each repair project (for example the kitchen cabinet installation or exterior doors) along with a cost listed for each line item.

I saved on buyer-side closing costs by representing myself.

You can easily call the city and find out cost of permit, or ask them to show you the receipt for permit costs.

It may be possible for a UPS Store to print it and have them pick it up to save on shipping costs?