Hi Aubrey,
From an electrical connection prespective your layout may be OK. Have you thought through a security plan?
Your cloud phones will be an attractive target for hackers looking for free international calls at your expense. I would be tempted to have them on a separate sub lan thus minimising the attack surface from other devices.
I have also done a little work with IP cameras and they can create quite high network traffic if you want motion video as opposed to time lapse. I would be inclined to have them on a separate lan segment. I used a dual nic server running zoneminder (which is a freeware CCTV monitoring package included in many linux distributions) as a good gateway to a CCTV system.
I would also put a DMZ router immediately after the BT hub so that you are in full control of your outer network perimiter.
EG