Yeah AT&T is not the best. Agreed.
To delete multiple emails at once you hit edit in the upper right corner, check off the ones that you want to delete and hit delete.
I hate MMS. Impotant to you so I will just leave it there.
On the battery thing, all of my travel is by auto so charging isn't an issue for me. If I were to fly I would have my MacBook and could plug right in to that as I do my Blackberry.
Back to the MMS thing, as soon as AT&T's network can handle it that will be there as well. Other countries have it already, but.....