Regarding creation vs EXIF date; the script action simply says “creation” date, but I'd like to assume it's the EXIF date. That said, if you're using this as designed, those should be the same, since you'd be copying it off the card which would have an identical file creation to EXIF date. The only reason I can think of that the creation date would be different is if there was a network copy involved, which sometimes messes with file dates. At least that's what I'm thinking. 

To not keep the original file name, that seems a lot harder. I don't know that you can use wildcards in here (i.e. to replace the text “IMG****”). But if you're just trying to rename all your files with simply the date and time as in your example here, I'd say skip the AppleScript and just use NameChanger or Better Rename. In Automator there doesn't seem to be a good way to delete a text string, just replace it, unless I'm missing something. You could undoubtedly get into custom AppleScripting to do this, but that's beyond what I'm familiar with.