Once you are in the park they will not need to scan the park ticket again as long as they stay in the park. If they leave the park and want to get back in or go to the other park, they will have to scan the park ticket again.
The photo pass is a separate card that will need to be used each time a picture is taken. Most roaming photographers will take a picture of the bar code before taking your picture. If there isn't a photo pass card for them to use (someone else in your group has it), they will give you a card that you can scan later to add your pictures to the photo pass account. For the ride photos, they can show the card at the kiosk or at the desk.