Smoke alarm maintenance

 I posted these questions on the end of another topic a couple of weeks ago but did not get a response. I am adding as a new topic hoping some one can help me with my queries;

1. In our block (1970s NSW) the smoke alarms are battery operated and installed after construction. I am not sure but I believe they were installed by the OC, notwithstanding I take it from the information in other posts that the alarms would be the lot owners responsibility, is this correct?
2. We have an annual fire safety inspection which includes smoke alarms. From information in other postsI gather from that these inspections are a statutory requirement. Is this correct?
3. We have not been displaying the inspection certificate on the notice board. Is this mandatory and if yes could you advise where I find the requirement?
4. If the inspection reveals the smoke alarm requires repairs, replacement or new batteries can the OC undertake the remedial action and then bill the lot owner?
5. In the answer to 4 is No, what action can the OC take to ensure all the smoke alarm is serviceable?