(I know.. vague answer) but it probably depends on so many factors: if they are sf or multiplexes (which have some economy of scale); how much work you are farming out (like are you doing it all or using some mowing and plowing or handyperson); how long you keep tenants; the age and condition of the buildings; the quality and type of tenants; even factors like your health, job (flexible or 9-5 all day 5 days a week); and more... all that said....I have done 10 with not an undue amount of trouble and worked full time with flexible job...And I know I could do more, but my wife looks at me funny if I get too busy working on rentals....

Yes, I forgot to mention that your REIA may be able to offer a health care plan.

She mentioned that their health is declining and wanted to cash out some of their properties.

Department of public health? 

There is no incentive for you to hire a mold inspector and chances are the mold is not a real health issue.

I have spent a fair amount of time "investigating and researching" aspects of business and real estate the last few years, but do to some health issues, there hasn't been time to execute.

Currently I am working for a Health Insurance company but I don't plan to spend the rest of my life there.I am ready to start building my future. 

To find seller financed buildings, the owners have to be motivated in some sort ( retirement, bad health, etc) and you have to be able to solve their problem.  

We told them we weren't raising rents at this time (that put them at ease and gained their trust & cooperation), then we inspected all the units and focused on health & safety issues and deferred maintenance.

In our area the health departmment will come out and do that.