Sounds like it is best for you to just view them in store. Because of your experience with the Nexus, your perspective will be different. The Air is for someone else in my household, and I still have the iPad4. If you are still happy with your iPad3, then it might not be worth the upgrade to an Air unless you want lighter weight, faster speed, or more memory. I went with the Mini because I wanted something more portable in my handbag, another night-time reading option and a cellular connection. I travel frequently on business. I thought the Mini might be a reasonable option instead of carrying both the iPad & eink reader plus laptop.
I have the same camera.
Interesting setup that you describe. My passion is landscape photography. No shortage of opportunities here in the American Southwest. An easy drive to the coast, the desert, and the mountains in any direction. I have one of the Apple adapters so I can access my photos. It works for me. Years ago when digital photography was new and tablets didn't exist I used to travel with a portable printer.