Hi, thanks for your suggestion.

Fields that are marked visble and unvisble on profile should be indicated as such

This is a great feature but is more complex because the system must calculate the usergroup and ACL of user after registration, I think the best way is to set this information on description of field, the system will render a Tips on form

In many european countries the law requires the user to actually take notice of the terms and conditions.

I agree but this is not simple, depends of law of countries and of law that regulates the discipline of the site:
example: in the insurance branch (Italy) you must have Accept,Not accept with radio and when user check not accept the form must to send an alert and the form will close.
- in other brach you can use a checkbox,

Unfortunately, there is no general rule. In you case you can simply add some javascript code to:
- Disable a required checkbox on document ready
- Enable checkbox if user click on link in Delimeter HTML