I said that I was trying to purchasing a rental and I asked him what he purchased it for and what was he trying to sell it for.

Jetting is simply pressure washing the drain field lines from inside, and all it requires is a high pressure hose with a special nozzle and a pressure washer.

Was he still in the service when he moved?

Nurses wash their scrubs every day and sleep odd hours.

So it sounds like the deposit issue is a wash, and I can depreciate half the roof now (even though I live upstairs in an up/down unit where the roof fully covers my residence), and the other half if/when I move out and rent the top unit out?

Huge wash out in real estate .. just like we see the wholesalers come and go on this site.. its the same business you putting two people together for expectation of a fee.. its a tough business. 

One other item to (politely) hit your neighbor over the head with is the fact that a tree's roots will continue to grow for months AFTER it is cut down.Suggest to your neighbor to have a sewer service use a cutter blade and clear out his line, and then use an acid wash on a regular basis to keep the roots from overgrowing his sewer.  

That is DEFINITELY not the story with laundromats/car washes.

Water is still on at the house so they must be using the sink to wash dishes. 

I see one, cold water line run from point A to point B, which appears to be near the washing machine.