I have a Duplex that is a century home I would like to update the kitchen with new cabinets and flooring.

I have separate folders on excel for each property, when I pay a bill or spend any money on a property, I record it in that properties folder as well as put the receipt in a separate folder in a locked file cabinet.

Renovation takes time, hurts occupancy, and if certain things (like kitchen cabinets) are in the middle of their life there's no need to look a gift horse in the mouth. 

Drywall is in, but it needs flooring throughout, kitchen cabinets/counters/etc, bathroom showers/vanities, new roof, and possibly new windows/sliders throughout.Any recommendations?

However, my brother and I did the labor, framing, vinyl siding, plywood floors with carpeting, contractor grade cabinets and post form counter top.

Things I have found renters care less about than I do: new cabinets, fancy light fixtures, specific types of flooring (other than no carpet), granite countertops, outside landscaping, fancy siding, heavy curb appeal in general, fancy appliances, and probably other things I can't even think of off the top of my head.

In our home they drywalled over the AC vents, cabinet pieces were falling off the wall, appliances were installed improperly, and many more problems.

Missing a/c unit, both toilets, kitchen sink( no pun intended ), hot water heater, cabinets, part of the back fence.

The new house would have in-floor heat and a piggy backed combi-coil for potable water....a very efficient system. cabinets are all straight with no bends so counter tops are dead simple and cheap.

I personally think the under cabinet lighting would give the kitchen an awesome look, but I prefer the shorter cabinet above the sink.