In Victoria, the Surveillance Devices Act 1999 applies.
IMO, the main parts of that Act, applicable to an OC are s.6 and s.7:
6 Regulation of installation, use and maintenance of listening devices
(1) Subject to subsection (2), a person must not knowingly install, use or maintain a listening device to overhear, record, monitor or listen to a private conversation to which the person is not a party, without the express or implied consent of each party to the conversation.
7 Regulation of installation, use and maintenance of optical surveillance devices
(1) Subject to subsection (2), a person must not knowingly install, use or maintain an optical surveillance device to record visually or observe a private activity to which the person is not a party, without the express or implied consent of each party to the activity.
So basically the OC should not record private conversations or private activities without consent. Most CCTV installations don’t record sound so the issue is generally about vision only. As long as the cameras view public or common areas and do not view into areas where private activities could take place (eg into the private apartment areas) and if signs state that there are CCTV cameras in the area (which some say is the implied consent), there shouldn’t be any legal problems.
Access to the vision is up to the OC to decide. Eg the committee could do it on a case-by-case basis if that was their wish. Some OCs allow live footage of the street door and lobby areas – similar to intercoms. Some don’t.
AFAIK there’s no rules on how long the vision needs to be kept. Most CCTV systems can be set to automatically overwrite the oldest recording. It means that the size of the system’s hard disk determines how long the vision is stored.