Hi Chak
I believe in almost every instance the reponsibility to have a working fire alarm is with the individual owner. Most strata schemes enforce an annual inspection to ensure this is the case.
With regard to the deadlocks: yes, you can install a deadlock, but there are certain types that the fire safety companies state breach fire regulations (barrel locks and those that need keys to open/close spring to mind). Your EC may have details from previous inspections, or you could get in contact with the company that does your annual fire inspections as to which deadlocks are recommended. Also, bear in mind that fire safety laws are retrospective for units, so just because a deadlock was up to code in, say 2003, doesn’t mean that this is still the case.