During the inspection we noticed some water seepage in the basement. 

Yes you need to budget for it even if you are doing it yourself.Is it near the water?  

If you look at it purely as a cashflow play, then I think that changes how you evaluate the purchase.

The tenants are on separate electricity but the owner is paying for the water which is a min. of $120 mo.There is a property across the street for sale for 125k.. he said himself that was too much and mentioned lightly he would sell his for 110k.

It is lucky a roof even lasts for 40 years no matter what the material is...You may also keep an eye on other expensive things like water heater and AC. 

If only one lot is empty, I would check if it is in a flood zone, or if there is storm water easement in the back or side.

The rent from my roommate and the second unit of the duplex cover my mortgage, insurance, taxes, maintenance, cap ex, vacancies, heat, electric, water, and internet!

@Jesse Waters I have asked about Blakent loans but didn't get much of a response from the lenders I asked.

I know there's enough space to convert, but I'm interested in understanding the path better.I know I have to (not in order of importance):1) add an additional entrance for 2nd unit2) convert a bedroom into a kitchen plus3) get additional electric/gas service4) submeter water?

If you are buying and holding then the nets to work into your analyses would be: (1) mortgage, (2) maintenance fees, (3) property taxes, (4) homeowners insurance, (5) water bill, (6) property manager if you do not intend to manage it yourself, and (7) future property maintenance, suchas roof & painting, and concrete.