Actually, for # 2 I think you can change the tags while the books are on the device through Calibre.
While your reader is connected to the PC and Calibre is open click the device that the books are on in Calibre, either the main memory or a card. The edit metadata box is not available but if you click in the field on the book listing you should be able to change it.
I'm at work now and can't test but I've updated the book and author name this way many times. Sometimes these fields will start to display a weird character for the last letter of the book and author name and I've always been able to correct it this way.
Good Luck!