Quick question

If i get a user to sign up say only asking for an email and at a later date or in another form i ask them for more details like the email, name, address and so on would this just update the existing record for the user or add a new record???
You can send to users campaign with [UPDATE_PROFILE_URL] tag. This tag generates a link, where the user will be able to enter their additional info.
Does mailwizz detect from signup forms, if an email address is already on a list (or in any of the databases) and then adds (not yet existing field data) to that subscriber's record?