Great Wall facilities,photos and time

We're looking at taking a SNA tour to this section of the wall in August. This is the MOST important thing for me in China. How much time does one need? Is an hour sufficient? I'm big into great photos...are there photographers there? Is it usually busy in August, or can one get good photos? How about washroom and water...are they accessible? I was thinking of maybe getting there with the tour group, but staying and getting back on our own to our Beijing hotel...do you think that would be hard to do? I'm feeling very stressed about having to rush.