...which then leads to a question "is there any wireless keypads that work with Elk?" The answer is none.
And how bulky can a wireless siren be? AC and battery backup is no big deal.
Is there such thing as wireless RS-485 that connects to the data bus? Costly to make.
Do pro-installers install security systems in a rental apartment?
Very few mfg's make wireles keypads that I know of (Ademco and GE I beleive).
The wireless sirens are bulky. Ademco has one. It has to plug into an outlet and then be screwed into the wall it is so heavy.
Yes some pro installers do installs in rentals. The Ademco Lynx is very popular for that and possibly the EK Guard might work for that as well although I have never seen one and tried it.