AOC and DAC are very different under the hood. AOC (Active Optical Cable) requires additional power for the electric and optical conversion. DAC is passive copper and doesn’t require any additional power. (there are also active dac cables that have longer reach). The Ex3300 hardware compatibility page doesn’t list any AOC as compatible, so you’ll probably need to purchase some DAC cables. I’d go with the same part number your friend let you borrow since you know those work.

Cat6a can do up to 10gbps, I don’t see a reason to go 8.1, unless you expect to outgrow 10g.

Is this connecting to a managed switch? If so, you need to see if it supports port security. That way you can lock the port to the MAC of the camera.