Factory Alarm questions

I have owned my 740 for 1 year now, and just found out that it came with the factory alarm fitted (thanks Shogun) Can anyone tell me how the system is armed? I have the 2 button key/remote that locks/unlocks and deadlocks doors, is the alarm armed when doors are deadlocked? The light on the centre dash vent flashes when deadlocked, does that mean it's armed? Does it have a siren or a horn? She came with a circle key that I have seen used for isolating alarm sirens on some of my other cars, but I haven't seen a siren whilst working on her. Does the factory alarm imobilize the engine? I have tried to find information on the web, but most are vague or in a different language, is there a site that I can find out more info on?

any information would be appreciated as I don't know if the alarm even works or if I am missing parts (remote buttons?)

Factory Alarm questions