You can use an NDI camera or an SDI one, both will allow for network control, video, and power with just the ethernet connection. NDI is just a form of network video that is very high quality and has very low latency for network video. You don't need cat7, cat 6 should work just fine (that would be the cabling for NDI). The camera does have HDMI or SDI outputs or the rs-485 or rs-232 for serial control, but you don't need to hook those up unless you plan on using them
You can bring the audio into the camera, and pull the into OBS with the video feed of the camera, or run the audio to the computer running OBS and pull in the audio that way. We usually suggest using an audio interface to pull in the audio directly to the computer running OBS. The line inputs on the cameras work, but they are not the highest quality audio out there, they are more for reference over anything else.