You can start meetings via the Web SDK by passing in
1 for the role when generating the signature.
Yes, as long as you have a different meeting host for each meeting.
In most cases we do not allow white labeling unless you are a Zoom partner. If you want to inquire about a Zoom partnership please let me know.
To use the Web SDK you need at least 1 pro or above account. Then depending on what functionality you want, you would need to pay for each additional meeting host if you want to host multiple meetings at the same time.