They can pay the rent and security deposit before the beginning of the month and move in anytime that is convenient for them.

It's a good method for people like you who are in self employed situation. 

You may want to check out this thread:https://www.biggerpockets.com/forums/52/topics/383631-method-for-tracking-income-expensesI described my tracking spreadsheet, and there were some other interesting posts as well.

I've heard about Goldman Sachs and other large institutions buying thousands of loans and holding on to them (punishment for the its role in packaging and selling toxic mortgage-backed securities in the housing meltdown).

It depends primarily on what price you are willing to pay for physiological security.

There are many ways that the IRS has deemed appropriate to allocate tax basis between building(depreciable) and land(non-depreciable).One method is that you may want to see the ratio of land/building allocations of recent homes sold in your area.

This method leaves a lot of stress and unknown factors off the table and limits the pool of potential buyers to serious investors instead of dealing with the potential issues of individual buyers looking to buy a owner-occupied unit. 

Property Location: Moss Point, MIssissippi32 unit complex4 buildings sits on 2 acres and all units are on the ground floorAll 1x1 units (Market Rent: $500/mo) 60% Occupied ( most occupants are long term social security recipients ) Per the seller (seller from out of state) all vacant units just need cosmetic rehab to be market readyPotential Gross monthly income: $16000 ( all units rented and are paying market rate) Current Total Gross Income: $7400 ( due to vacancy and residents paying BMR) Current Monthly Expenses: $1941Monthly Note Payment: $3419.43Asking Price: $660,000Seller Finance Term: - Seller wants to be cashed out for the amount left over of the loan balance ($295,000).

I am not aware of any jurisdiction that will allow you to do it on your own as you must first start with a survey and grading plan and then the engineer will determine best practical methods for the stormwater.

He would be secured by a second position.