MailChimp: Can WP registration include MailChimp groups? And how to unsubscribe?

After adding MailChimp Sync, all my WP subscribers are now added to my MailChimp subscribers.

Question 1: If I create groups in MailChimp, can I link these groups to the WP registration form so WP subscribers can select their groups of interest upon registration?

Question 2: If someone unsubscribes from my MailChimp email, does this automatically remove them from my WP subscriber list? If not, then what is to prevent the MailChimp Sync from adding the unsubscribed email address from WP back into MailChimp, thereby causing a spam situation?