Dear Salman, non of the verses say wives at the same time. Please note whenever talking about Prophet wives all ehkammats were for all the wives whenever they got married with the Prophet SW. That is not to say there was no divorces or any of them never died.
Also note Prophet's wives, whether they remained as Prophet's wives or not, were told that they'll become all beleivers' mothers (33:6) once they enter into a marraige contract with Nabi SW with more stringent rules and punishments. That was basically to protect Prophet SW from being exploited through women by his enemies.
And I don't think I need to remind once a mother always a mother. One cannot ever marry his mother whether divorced from the husband or not!
For Surah Tehreem please read my reply to brother Habib.