About Photos:
I wouldn't worry much about photos in prep at all, unless your site really cries for them (or it's required by your mentor). I think in my second review, my mentor suggested that I use a picture for a specific article, and I did so. That was the only picture I used in prep.
Now I try to use more pictures, because I think it brightens up the site and adds excitement. However, I place a much higher emphasis on content than photos, which means that there still aren't many. It's just not that critical for my type of site. If I were running a site like Geology or Forestry, that would be a lot different.
Once you become a Guide, you get more options for picture sources. About has a deal with Getty Images, and I believe that the health guides also have a source of images. For a side like ADD, your content is going to be what's important. Maybe one pic to show you can use the tool (the brain diagram sounds good).
About Guide Photos:
Mine took a while to put up, too. I really hated that ghost-like grey picture, so I was so glad when it was gone! I think it was a couple of weeks before it went live.
About the Site Being Removed from the Application List:
My site also disappeared from the BeaGuide list before I was notified. So I think that means you're getting close!