Hi Denise!
How terrific! From the accomplishments, to the wonderful years spent with your soulmate, this must be an exciting, rewarding time for you right now! From all of us at the panel, our congratulations to you and your family!
The Pirates League at Magic Kingdom (Adventureland) is a fantastic experience, and one I recently did with my children last December. To answer your questions, there are no photographers taking pictures while the children are getting their makeup applied. At the end of the indoctrination process, however, your grandsons will be taken to a special room. In that room, there is a photographer getting a good posed shot of your newly minted pirates. Those photos can be purchased during checkout if you so desire.
Be sure to bring your own camera as well, though. You will have ample opportunity to take as many pictures as you like before, during, and after the pirate transformation. While getting their makeup applied, you will be really close to the action. They will have benches in the area to sit, or you can elect to stand by your grandsons as they're getting prepped for pirating.
4 adults is fine, as long as the Pirate Masters have room to do what they need to do, and no one is getting in the way, it shouldn't be a problem. Our family of 4 was all back there and we saw other whole families watching their children as well.
So good luck, congratulations again, and have a magical time on your trip!