1. Mozilla is still working on it 2. It's possible to add that but it might break some sites where people set their delay to 0, so it's safer to do it on tab close (with a delay). 3. Browser Start up cleanup only cleans unused cookies (normal Cookie Cleanup) + GreyList cookies, unless you enabled "Clean Cookies from Open Tabs on StartUp", then it's (normal Cookie Cleanup) + GreyList cookies + Open Tab Cookies.
