You want to do Ultra HD, but are you aware your Sony PXW-Z190 don't have a 4K output? These units are HD output only!!
The Z280 does have a 12G-SDI output
Television Studio Pro 4k would be the mixer,
Ultra Studio 4K is only a capture box. Not a video mixer.
I would not go for walkie talkies. The audio is very small banded and is very hard to hear in loud environments, unless you invest in very expensive heavy duty headsets. Still audio is small banded and sounds crap.
For Fiber it is 1 cable per camera. Go for some heavy duty fiber cable and not just LC cables, They will damage and break in no time.
For example look at FieldCast Fiber. We use it now for several years in rental environment.