Hi Nico,
Thanks for reaching out! This is possible however it will require two databases, one being the sign-up form, the other being additional questions.
You will need to add a Custom Member Page, this is a two-step process by creating the database and creating the members page.
You can read more here: Creating Custom Member Profile Pages
As for Pipedrive CRM to the member’s area, this would require Velo implementation using our available API’s to communicate with one another.
Please feel free to reach out to the Velo Forum for further assistance with this aspect.