I have been looking at this arena easiest way to get a quick look ay what you can do is download PiVision.
That article gives a rundown but its so easy just to pipe the camera through netcat.
You can do it from the command line.
raspivid -p 0,0,640,480 -t 5000 -o – | nc  5001 -w 640 -h 480 -fps 30 -b 1777778 -v -br 50 -co 0 -sh 0 -sa 0 -awb auto -ev 5 -ex auto -rot 0 -mm average
The Python lib picamera is excellent and its more of what you can not do than what you can do as you will have to take a look.
The camera in the link is like $150 !!! its $30 for a v2.1 cam and a Pi Zero and depending on how you connect wifi / ethernet its a dongle or go usb and set the zero up a an ethernet gadget
2x Pi Zero could so all the preprocessing and stream to a Pi3 and get power and ethernet over usb.
Not sure why you want a stronger pan/tilt mech (big lens?) all the main stream pan tilt mechs I have seen as still direct drive and its the servo.
I think you can swap out the towerpro SG 90 for MG 90 which have metal gears.
Also the openCV stuff has examples for streaming.