1. Standard ELM327 devices are just "router", that provides communication between app (smartphone) and car's ECU. So no "active" function is supposed. ECU itself also only "answer" to your questions. The only "active" node in the chain is app, that must send request of a specific parameter, than analyze the response and trigger some action.
2. All above works only for parameters specified with OBD-II standard, that describes Engine and Exhaust system parameters. All other car systems like Alarm, ABS, SRS, etc. does not covered with any standard. Appropriate commands and parameters are very specific to make-model-year and have no public information. You might look for a specific solution that declare Alarm system support for your model
Thanks!