Yes, turning the Chip Dumper 180° will position the open side down.
I do my lighting through the hole at the beginning point of the maze (There's one on each end).
Below is a good Thread on lighting the AMNPS. It has a good video, and Post #2 gives my Basic method. Getting it lit properly is 99% of the job, and putting it in the best place in your Smoker.
I have never used a Mailbox for anything other than Mail, and mine doesn't go out in any of my Smokers (Gen #1, Gen #2, or Gen #2.5).
Link to Lighting AMNPS:
http://www.smokingmeatforums.com/t/140859/how-i-light-my-amnps-w-video-link
Bear