Landscaping can be routine lawn care, snow removal, and can get into tree removal/trimming, new mulch, etc.  

The wall would be Another $200 in supplies and I have spare doors and trim.

Now, if the screw used was too large and split the trim, that can be damage as the tenant was negligent in using such a large screw.If woodwork is at a higher end, unusual such as solid milled hardwood, and that is defaced, then that can be damage, your lease should also state more specifically the care expected to such features.

The damage it left on the trim and one of the doors is easy to quantify.

This one was secured against another property also. 12 months at 10% interest only payable monthly.I put $8k into new flooring, paint, new AC, siding and trim repair, some electrical work, new fixtures etc.  

Additionally some of the costs such as updating the electrical panel and trimming trees can be included in the cost under site preparation expenses.My question is how to what extent is site preparation allowed to be included?

You may want to regrout the tile for a clean fresh white, which will make the pink and black pop. similar to the pop you get from white semigloss trim/baseboards. 

Some stuff was better, some stuff was worse.Better: old-growth wood floors and wood stud and floor joists/roof supports, double-brick cladding, expensive trim and molding, tall ceilings, solid wood interior doorsWorse: foundations; virtually all systems (plumbing, electrical, mechanical); insulation; lathe & plaster (this is a subjective opinion); windowsMy personal preference these days are houses from about 1955-1970.

If you want more cash flow, trim down the number of units and stay afloat with 100% equity on all the properties with highest appreciation rate.

(floor, trim, paint, fixtures).