Courses and course formats

Dear all,

as a new moodle user, I have some questions ;

• how can a course be removed? Is it possbile in the web interface?
• is it possible to have a 'directory' like overview of all courses, i.e. possibility to collapse certain categories?

In our strategy, we decide which users should follow a course. So enrolment by students will not be allowed (by means of enrolment key, because there is not other solution), as well as unenrolment. Therefor, is it possible to

• enrol users via groups (and not on individual basis, as we're dealing with large amount of people)?

Thanks for the consideration and time.
Kind regards,
yves