I agree, if you have a finite and reasonable number of possible errors, the puppy/colored box idea should work great as long as each different error icon is unique enough (i.e., a puppy icon and a kitten icon would be fine, but I would avoid different types of puppies...the user will remember they saw a puppy, not necessarily what type of puppy).
Other possible ideas would be to just assign a number to your error and make it flash. Flashing gives a sense of urgency and, as long as your list of typical errors is small, the user should be able to recall a flashing number. If you get into the hundreds, this might not work so well.
I can't add anything to the RF debate, but be aware that being next to any major bit of infrastructure can be a real pain in the ass.
He's already decided to live near a major piece of infrastructure, that being his building's roof. I lived in a top floor apartment (real apartment, not a condo) in the past, so I know how it is. Lets just say the guy on the top floor reports more roof leaks to management than the guy on the first floor. If the roof leaks all the way to the first floor, you've got real problems. It seems disturbing to have contractors occasionally stomping around on the roof, but its actually less annoying than having residents stomping above your ceiling all the time. Also, even in cities, animals live on roofs. Loud animals that chirp at sunrise and creepily scratch at the roof at all hours, and they build ugly nests out of trash and crap all over your windows.
Another interesting point is about two decades ago I turned down an entry level job of visiting cell sites and running periodic sweeps on the antennas with a spectrum analyzer and TDR the feedlines, along with visual inspection of the antennas and equipment. You'll have a regular "scheduled" visitor, not just repairs and upgrades. I imagine it would be about as annoying as having a water meter reader visit, no big deal, just be prepared for it.
An Ada exception is when a routine gets in trouble and says 'Beam me up, Scotty'.