We used 2 disposable cameras for the full. We started with one and then changed cameras when we met up with our scream team near mile 13. It fit nicely in a pouch in my fuelbelt. Some of our better pics are from our cameras (as opposed to the professional ones that don't seem to catch too many characters.)
Speaking of pictures with the characters, when we were running through MGM we got our picture taken with Mike & Sulley from Monsters Inc. The character handler used the PhotoPass system for that one, so we had a professionally taken PhotoPass picture of us in our running outfits!
The handlers will allow you to cut in line if other non-runners are in line for the picture with the characters. When we stopped for a picture with Aladdin and Jasmine, there was a group of people already in position for a picture. The handler moved them out of the way, took our picture, and then had the group get back in position. We would have been fine waiting until the group was done...but I guess the runners have total priority during the marathon.
One word of advice...if you are going to do lots of pictures during the half, make sure your flash is on. It was very dark when I got to the MK for the half, and a couple of my pics did not turn out because I did not turn the flash on. By the time I got to Mr Incredible in Tomorrowland I had it on, but I missed out on a Castle Photo op.
Take lots of pictures during your event!!
Paul