The realtor would then want a guaranteed number of hours, then it becomes an argument and battle when you could have a cash cow STR.  

You're halfway through the battle with the statement you made about following the letter of the law... now just seek the advice of a professional about doing it.Cheers!

You should also check to see if Fair Housing even applies to you because many small Landlords do not have to abide by it.It's an uphill battle, usually not worth fighting.

Frugal fouls of burdening others in any way must be avoided!

I am also scared that somewhere in the slab (although no indication of that) and also in the shower and toilet (again no indication of that, water flushes smoothly to the sceptic and no funny smells outside) the plumbing is bad.

Never paint brick you dont need to, clean up bushes or remove near path, less maintenance, rake yard, colors work as is , just make sure in paint in good shape, maybe newer lighting say motion sensor, a nice kick plate to door would brighten up, and reduce wear, throw in some real cedar chips near door for cedar smell, house colors are fine and wont bring in more rent or faster, just make clean & inviting, put mat near door so stays clean for showings, and worry more about inside

My wife says I smell like dirt... 

The smell of fresh cut grass is the best smell in the world and a good looking lawn is admired by everybody that drives by.

No harm no foul.The way you are asking, it just don't pass the smell test. 

D class is just this constant battle and frankly I cant imagine a worse job than being a PM in D class property.. tenants are abusive owners TOTALLY unrealistic.. sell it and buy something nicer is the answer.. your D class returns will never be what yo think they should be or what is projected