Thank you for posting in the developer forum-- I am happy to help. Zoom considers a meeting as ended when the in meeting option "End Meeting For All Participants " is selected. More details on in meeting controls can be found in our help documentation here. Please see my inline comments to your questions below:
→ A meeting is in a start state when a host starts the meeting via Zoom client or start_url. If the option “join before host” is enabled, the meeting will be considered started when a participant joins the meeting.
→ If a host leaves or drops unexpectedly and no participants are presents, the meeting will continue for a few mins before ending. This allows the host to rejoin if they left accidentally.
→ Correct, if Zoom does not receive any request to start the end the meeting, and there is no user activity, the meeting will automatically enter into the end meeting state.
Please let me know if this answers your question.