I've done Zoom professionally with as many as 1000 participants simultaneously. The way to do it is to go through the settings in the Zoom web portal, making sure they're all correct, and then do a dry run with other people so you get familiar with all the controls you'll need to use. Have them try to break your meeting. Do you know how to find and mute that one careless participant without muting your presenter? How to lower hands? How to lock the chat? Use the desktop app if you can, since there are more features available.
Each point is addressed by a different option in your account settings:
- It depends on "How many participants can share at the same time?" I have never seen a need to allow multiple simultaneous shares. This is per room, so you can use breakout rooms to allow multiple screen shares.
- It depends on "Who can start sharing when someone else is sharing?" As the host, you should be able to stop other people from sharing, so I wouldn't allow participants to be able to interrupt each other.
- It depends if you "Allow removed participants to rejoin". Turn this off and make sure that you or your co-hosts don't remove users accidentally. (The only way to allow these users back in is by restarting the meeting.) If you need to temporarily remove people from the room, put them in the waiting room (another essential setting to have enabled).
Note that the screen share settings can be changed during the meeting. If you only need to allow others to screen share at the end of the meeting, consider keeping it off until then. On the other hand, you need to be (or have) someone who will remember where the settings are under pressure for that to work out.