I'd be glad to help with anything I can, I'm in Calgary about an hour away from Banff and I lived in Jasper for 6 years previously.
It sounds like your coming during the Calgary Stampede July 8-17 so that is probably not going to help with campground vacancies.
Tunnel Mountain is the big campground in Banff but there are two sites, Village l and 2. Village l is the upper one and is far nicer IMO.
Banff can get pretty busy in the summer but there are provincial sites like Mt. Kidd and other Bow Valley campgrounds in Kananaskis. (Between Calgary and Banff)
Alberta parks (not National parks) has a newish reservation system that will be taking reservations Feb.22.
Campgrounds in the area do fill up quickly.
For some deluxe camping check out the Fairmont Hot Springs Resort in B.C. I'd say it's about an hour away from Banff.
For photography I would definitely say the Ice Fields Parkway up to Jasper is second to none. If you do make it to Jasper and like to fly fish, Maligne and Medicine Lakes are my all time favourite spots.
There's a few off the top of my head but glad to help.