Real-time voice or video communication between users on mobile devices or computers
Hi 15YM
Greetings
Thank you for posting in Microsoft community.
To answer your first question , Microsoft teams has the together view and large gallery view, and the large gallery view allows you to see the videos of up to 49 other people at once, and this option is available when at least ten people have their cameras turned on. For further information on the together view and large gallery view kindly see Using video in Microsoft Teams - Office Support
With regards to your last question, according to the official article Differences between Microsoft Teams and Microsoft Teams free - Office Support there's no mention of limitations of cameras that appear on the screen.
Please feel free to let me know if you have any further questions.
Regards,
Momo