Labor for removing old/installing new sink, cleaning, painting, etc?  

If you buy post-1978 you likely miss all of those lead-based paint, galvanized plumbing, knob-and-tube wiring, asbestos, etc. issues.

All units will need updated kitchen (plus appliances), bathroom (plus new tub, vanity, toilet), expansion of kitchen in one unit, whole new kitchen area for another unit, new floors, paint in all units, plus new HVAC, plumbing, roof...

New bath tub/tileNew FlooringNew Paint/TrimNew Vanity/FixturesNew Sink/Toliet

Paint, carpet/flooring and lights.  

We've done some small value adds - painting, new appliances, new counters, along the way.

Usually there are minor repairs, new locks, painting, repairs on the floors etc, and then we usually have a realtor who finds us a tenant property.I wouldn't let a tenant out of that responsibility. 

Painting - there are holes from hanging pictures and some spots that need touched up.

There is not much work that needs to be done, just a little dry wall, paint and a backed up sink in the basement.

Thankfully, the contractors left the paint and some other things.