New roof, scraped popcorn ceiling, paint, texture, flooring, new appliances.

For about $150 or so you can install a nice light/ceiling fan/heater in the ceiling of the bathroom. 

There are lots of different types of issues such as a deteriorated chimney, holes in the siding, a hole in a ceiling, and guard rail/deck repairs.

All that paneling says Kenmore, but the dropped panel ceilings and lack of windows says Buffalo (Kenmore homes are too short to add a dropped ceiling).

Along with the ceiling fan not working, oh they didn't turn the light switch on for it.

As far as an 1885 basement (assuming it looks somewhat like the ones we have here in Milwaukee) finishing is not a great idea and here is why: you are probably lacking ceiling height and windows, so the result will produce only low rent.

I actually had an investor talk themselves out of a great rental because they didn't like the textured ceiling.

Briefly mentioned above but very important is the semi sharing of space (in this case shared ceiling/floor) as well as outside. 

Drywall for walls and drop ceiling etc3.

We did some small renovations, flooring, paint, scraped ceilings, etc, moved into one unit, and put the other up on AirBnB.