Microsofttritool, with regard to (1) it sounds as though you may want to try another driver version. Does the same webcam focus issue happen directly in the Windows 10 Camera app?
With regard to (2) the keyboard shortcuts for Teams are listed at https://support.microsoft.com/en-us/office/keyboard-shortcuts-for-microsoft-teams-2e8e2a70-e8d8-4a19-949b-4c36dd5292d2 - no zoom options are listed for "meetings and calls" but for the Windows desktop app, Zoom in CTRL = and Zoom out CTRL - are listed.
The shortcuts listed at /keys within the app also show Reset zoom level CTRL 0
The combinations you mentioned aren't listed on https://support.microsoft.com/en-us/windows/keyboard-shortcuts-in-windows-dcc61a57-8ff0-cffe-9796-cb9706c75eec (either as general or accessibility shortcuts) but perhaps you have a another app causing the zoom issue (for instance https://docs.microsoft.com/en-us/windows/powertoys/shortcut-guide adds combinations with the Windows ⊞ key).
I tried the shortcuts you mentioned in a call running Windows 10 Enterprise 20H2 with Teams version 1.4.00.4167 (64-bit) with no additional apps installed and both CTRL + and CTRL = allowed the app to zoom (I couldn't zoom into the screen being shared) but CTRL - and CTRL 0 worked as well. The app settings were as follows:
Have you tried something similar to https://answers.microsoft.com/en-us/msoffice/forum/msoffice_o365admin-mso_teams-mso_o365b/ms-teams-zoom-stuck-at-really-really-big/870d1c5a-51da-4274-93a4-50497deab1b4?auth=1?
Otherwise, perhaps you could try clearing the Teams app cache (see directories that need to be cleared listed in the comments for https://microsoftteams.uservoice.com/forums/555103-public/suggestions/34320940-clear-local-cache-button?page=4&per_page=20), or sign out of the app and sign in again (does anyone know if that resets the app cache?), or raise the issue yourself on answers.microsoft.com?
