Misleading interface

While tending to some issue I had to face a piece of misleading UI.

The problem I'll describe here is somewhat minor. However, since it blocks that other issue, which is 'critical', I have to mark this one too as 'critical'.

This is how our bookmark editing form looks like:

Roles that may use this bookmark:
[ ] authenticated user
[ ] magician
[ ] student
If no roles are checked, all roles may use this bookmark.

There are several problems here,

First, "use this bookmark" isn't accurate. Everyone, even anonymous users, may enjoy the benefit of bookmarks --therefore utilizing them. We're talking here specifically about bookmarking content. So let's change this to:

"Roles that may mark content with this bookmark"
or:
"Roles that may use this bookmark to mark content"
or:
"Roles that may bookmark content using this mark",

I'm not a native English speaker, please help me here.

The second problem is that we use the term "role" incorrectly. In Drupal the anonymous user is a role too. We lead the admin to believe that if he chooses no roles then the anonyous user will be able to use this bookmark. (Note that our UI tries to mimic Views' UI, but Views also shows 'amonymous user' in its list.) What aggravates the problem is that in the overview screen bookmarks that are, supposedly, assigned to all roles are shown with the text 'All roles' next to them. On the other hand, bookmarks that are assigned to 'authenticated user' are shown with the text 'autheticated user' next to them. But these two cases are identical. We confuse the admin.

Moreover,

Nowhere we tell the admin that this module doesn't support anonymous users.

So let's change "If no roles are checked, all roles may use this bookmark" to:

"(Anonymous users may not bookmark content.)"

AND let's make these checkboxes a 'required' field. Currently the admin doesn't have to tick a role, so we have to explain what happens in this case. The current explanation is incorrect, and a correct one won't be very easy for the admin to instantly grasp. Moreover, making this 'required' will save me the trouble of deciding what to show instead of the incorrect 'All roles' in the overview screen. Let's clear the uncertainty fog by removing dilemmas.

So, overall, our UI will look like this:

Roles that may use this bookmark to mark content: *
[ ] authenticated user
[ ] magician
[ ] student
(Anonymous users may not bookmark content.)

(I need an English speaker here; the two sentences don't parallel: one uses 'to mark', the other 'to bookmark'. I didn't use 'to mark' in the second one because, I think, the documentation of this module doesn't use this verb. Or does it?)

BTW, If, in the future, we decide to support anonymous users --for 'global' bookmarks-- we will simply add 'anonymous user' to the list of roles and fully mimic Views' UI.