It would be helpful, that if the admin is logged in, a link to "delete this page" should be added (linking to thispage/delete).

just drop the following line somwhere in the footer.php (or in the header.php, whereever you want the link to show up):

if ($this->IsAdmin()) echo "<a href='".$this->Href("delete")."'>delete page</a>";

but i consider a deletion a grave step that is not taken too often. for me the actual mode works quite fine.

I would find it good to have it documented somewhere how you assign a user admin rights. Is this done manually in the config file? Does the field take a list, or a single user. And it would be good to have a link to this information on the delete page, since when you try and use this function and do not have administrative rights it just tells you that you cannot do this.

Just a suggestion.

It is done manually in the config file. The admin_users field accepts comma-separated usernames. For instance:

"admin_users" => "FirstUser, SecondUser, ThirdUser",

Is this compatible with http://wikka.jsnx.com/ACLsWithUserGroups ?

TimoK,
Good point. Except the question to ask would be; "is ACLsWithUserGroups compatible with how Admins are defined?"

If you'd implement "Admins" as a user group (page) and refer to that page in the config file, there would I think be a problem with looking up the admin's email address. The alternative would be to make sure that the config file contains only names of persons, not groups.
Neither would be hard to implement but ACLsWithUserGroups does need a little supplement for supporting Admins.

If there are attached (uploaded) files to a page, why aren't they deleted as well?

How do I delete a page when I don't have modrewrite active?

Nm foud it out myself, it's the same as with modrewrite active :)