Onboarding Polls are not required to start your Remesh Conversation, but adding some will allow you to create Segments to slice the data based on how the participants answer these questions.
If you do program Onboarding Polls, participants will be required to respond to onboarding question before joining the Conversation. If you ask any Onboarding Polls that may be sensitive, you can always include a "Prefer not to say" option.
You can learn how to program Onboarding Polls here!