Plugins Overview - which has a button for Check for Available updates and
links to All plugins + Additional Plugins

admin/plugins.php

Additional Plugins
./admin/plugins.php?updatesonly=0&contribonly=1

All Plugins
./admin/plugins.php?updatesonly=0&contribonly

Available Updates
./admin/plugins.php?updatesonly=1

Environment Check
./admin/environment.php

Debugging
./admin/settings.php?section=debugging

PHP Info
./admin/phpinfo.php

Purge All Caches
./admin/purgecaches.php