Subscriber lists/audiences in MailChimp

Morning! I have a question regarding subscriber lists/audiences. So I have multiple audiences so I can send specific content to each audience. Is there are way to set up: a. a sign-up form where they can indicate which audience/what content they would like to receive? (rather than having multiple sign up forms) b. if a customer goes to unsubscribe, am I able to set up the unsubscribe page to also give the option to change their email settings prior to unsubscribing? Thanks in advance for any help, comments & strategies