There's no "prongs" lol.More than likely smoke alarms will have to be hardwired on a dedicated circuit with an interlocking wire.When the panel is upgraded a main building ground will be required under article 250 of NEC.

I visit my property monthly when I do preventative manintenance - test smoke alarms, test GFCI receptacles, flush WH T&P valves, change AC filters and flush condensate drains, feel the bottom of sink drains, blow leaves off the roof etc etc etc...For a while I did the "call me when you need me" thing, until one day a tenant moved out after 1 year, and I went to the AC closet, and I saw 11 filters untouched.  

(Also required in your lease)Smoke alarms will get poked (& documented) very soon.

Also set alarms and notifications to new listings that match your criteria and keywords on the forums. talk to people, network if you can, and read, read, read, listen to podcasts... 

Maybe install an alarm on the fridge.

To be honest, I invest in Baltimore and I would not be able to invest without knowing exactly where the property is, hopefully it turns out well.I am assuming they are in an area where many other boarded houses available, so my suggestion get an alarm for it once you made some investing in it, it is very common materials being stolen.Good Luck, hope you get what you are looking for 

All 97 of them. 3 make purchases (a bit optimistic, but lets go with it). 2 buy 300K houses to sell them for 350K. after fees and taxes they set the alarm clock and make amends with there W-2 boss, vowing never to do that again.1 guy buys a 75K house with cat piss deep into the sub flooring, tarped roof$$$ (HINT HINT), and a collapse sewer pipe (orange burg$$$  another HINT).

Tapping PEX into existing plumbing is pretty easy as long as they were semi-competant and I don't find it super alarming that permits were not pulled.

Inspect for the smoke alarm and any maintenance/capex issues, and then be patient.

I WOULD NEVER TO BUSINESS WITH AN INTELLECTUAL PROPERTY THIEF!!