Hello Nidia,
Q1: This happens for many conferences. You know the when the event but don't have the sessions as you say nailed down. Have your invitees register for the event letting them know the sessions will be available soon. They will be able to login, using their email & confirmation number, to modify their registration, and choose from the available sessions.
Q2: We have created custom contact questions for dietary needs or accessibility needs. If you are not the admin or don't have access to create custom contact questions you can just use a text question widget. In the Site Designer there are the sections of Registration Information, Standard Contact Fields, Custom Contact Fields, and Questions. Just create a question "Do you have any special dietary needs?" and you can make the question optional or required to answer.
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James Rose | Senior Web Developer and Platform/Product Manager
Digital Infrastructure
Office of University Development | University of Michigan
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