hope that answers your question x "In a meeting" is the generally used phrase. "He is in a meeting". "I'll call you back. Right now, I'm in a meeting".
"...on a meeting" would only be used in conjunction with some other phrase, such as "sit in". "He sat in on the meeting". In other words, he is not normally part of those meetings, but he went in to observe for a bit. Another would be "Listen in". Other than that type of phrase (there are others) it will always be "in a meeting".
If you meet with, you have a meeting with that person, like a talk or lecture. Meeting someone is when you come face to face with that person.
A public meeting has to do more with businesses, basically a regular meeting. Meeting in public is just meeting someone like a friend or family member in public, like meeting them at a bus stop or restaurant.
Symposium originally referred to a drinking party and a meeting is a place to met others
A public meeting is one that is open to any and all people who are interested. A private meeting is one that takes place behind "closed doors".
Apologies: someone who can't make the meeting and informs the host prior to the meeting. Absent: someone who doesn't attend the meeting and did not let the host know.
A briefing is a type of meeting. It is normally used to indicate a 'feed' where information on a topic or situation is fed to the attendees as opposed to a meeting where ideas are exchanged and decisions made.
"It was a good meeting" - "good" is an adjective that modifies the noun, "meeting" "The good meeting went well" - the word being modified is "went", a verb. The modifier, "well" is an adverb.
i dont know the answer
As far as I can tell with the description you've given, A general meeting can happen at anytime, and on any subject, where an annual meeting will happen once a year, and will more than likely have a preplanned agenda. Of course a general meeting will have an agenda too