the most important thing is the photo. you can include gps data and custom tags just to speed up the process of creating observations, but it’s not required. personally, i tend to leave off gps data from sensitive photos, even though the system has the obscure/private geoprivacy thing, but i’m in the paranoid minority.
camera model is mostly just nice to know information. sometimes i’ll see a good photo and take a look just to see what kind of camera was used to take it or that sort of thing. but this is the only somewhat meaningful attempt to crunch that data that i’m aware of: