Anyone know if this is possible or can do this?

We provide CPR classes to companies and individuals on certain dates and times.

Each class has a location, company, date, and participants attending associated with each class.

Current Airtable setup: One base

Tables:

Participants, Classes, Companies, Instructors, Campaigns.

Question 1: We have 15-30 different clients scheduling classes each month. How can I create a client “portal” so they can add their own participants in a class on their own without having excessive users?

Question 2: How can we offer online registration with online payment, and each person registering is added to the correct class?

Question 3: How can we allow instructors to access classes they are teaching so they can add and edit participants attending on their own?

Question 4: How can we print custom documents for mail merge purposes so we can print all participants from a class populated onto one printable document?

Question 5: How can we email all of those same participants at the same time?

Thanks!