Additional team and channel-related features and issues within Microsoft Teams for Education
Hi Sir,
Glad to answer all the questions you listed.
Currently the default view when you join a meeting. If there are more than nine others in attendance, Teams will prioritize the people who have their video turned on, as well as those that are speaking the most. For people that haven't turned on their video, it will show their profile pic instead (or their initials if they haven't added one). In addition, the internet quality and the camera device play a part for displaying all the people in large gallery view.
We quite understand your 2,3 request and please terribly allow us current we cannot fulfill your request and we recommend you could post at the https://microsoftteams.uservoice.com/ and we will add our voted as well and hope this essential feature will coming soon.
Kind Regards,
George