Expressor is a SVN client and repository actions are really a function of the underlying source control system. If you want to see what projects there are, you can look at the list shown in Checkout Projects. If you need to see what is in the project, you would have to check it out so you can see the projects and libraries contained.
There is an article posted on the site that explains about a way to administrate project access more granularly. I have used this on our system so we have users who can checkout and update workspaces, but not commit changes. And, of course users who have full access. Not sure if that will help you manage artifacts.