Should I collect a security deposit, and upfront payment even though I'm sure he did that with the previous landlord? 

You need to know the following: *Location, Location, Location, How much rent can you collect in this location?

It needs extensive work before it can be rented and will keep me busy this summer for sure!

Multi-family units may very well end up comprising either the bulk or the entirety of my rental portfolio once I start collecting rentals.

I have been spending time studying materials on BP to know more about real estate investing.I plan to invest  in Nigeria and Uae but there are no post ,blogs or articles on BP that i have read so far that talks extensively or give strategies based on this two markets .So the challenge I have is that most of the post on Bp talking about stragies of acquiring a property and rentals does not really tally with the Nigerian market.

Medical costs  caused unpaid loans and collections to accumulate and to created a credit profile of a borrower who did not pay any of her legal obligations.  

My thinking is that this would help me do some more extensive flips here in the SF Bay area since properties are VERY expensive.

Their application is extremely extensive (seemingly).

I am thinking of purchasing it at his asking price, then lease-optioning it to another tenant-buyer with a non-refundable down payment of 40K with the option coming due within 3 years (maybe up to 5, with extensions).  

I'd also be interested in any aggregated source of data, if there is someone who collects data for multiple jurisdictions.Thanks in advance!