The last error is due to some sloppy programming

and the rest to some kind of error. To correct the error in the sent messages page, follow the following steps (all the paths indicated go from the joomla root directory):
Open /components/com_messaging/views/sentmessages/tmpl/default.php
Add the following code on line 5 (just after something with $document)
Save and close the file.
The other errors are caused by some configuration error. Could you try to save the settings again on the administrator panel?
Sander Kromwijk