I would remove the images or at least hide them somehow until you get a registered agent. You would be protected from the "Getty Letter" if a user uploaded a copyright image provided you remove the image as soon as you receive the DMCA take down notice. I do not believe it covers you for images that you download and place on your site.
As far as your main category photo I suggest taking them yourself or getting them from a reputable stock imaging company with no ties to Getty like Pond5, you can get images there that are great quality ranging from 1 to 25 buck easily.
Thanks for the information Robert...
I'll go ahead and remove all the images I used from WikiMedia and sxc.hu. Sounds like some are public domain, but I don't know how to be 100% sure.
I used those photos for the animal category "example" photos. Once someone opens up a category, the user-submitted photos are then shown.
The user submitted photos are "supposed" to be pictures that the owner took of their own pet/animal (but there is no way for me to verify that).
So If I'll redesign my site so that the user-submitted animal pictures are pulled for the main category photo (thus all images on the site are user-submitted), would DMCA have me completely covered at that point?