A:
Optics has nothing to do with your question
Each TV will require a certain amount of bandwidth for each video stream you wish to view simultaneously. If each TV is accessing the video content wirelessly (very not recommended - better each TV be on a WIRED CONNECTION to the main router), then you must assume there will be some degradation of the HD video when they concurrently operate.
If you step down the video resolution o something less than HD on some tv's you'd get away with using the wireless connectivity.
If you load TomatoUSB Firmware into the AC240 AND adjust the transmit power to 400mW, again you stand a better chance to support 4 concurrent TV's on the router.
As a throughput budget, I've had a pair of wireless 2400, transferring data wirelessly at 1 Gbps using a file transfer program.
Getting back to the optics service provider. If you're paying for the LEAST performing data plan, then it is unlikely the service provide connection will support the 4 concurrent TV's streaming!
..m