Do you now need a box for every TV in your home. What is the cost per box
Yes, you need a Set Top Box for every TV in your home. I believe the current cost is $6 per month per set.
You can avoid the fee if you own Roku's. To use a Roku, you must also be a Spectrum Internet Customer. The Roku takes the place of a Set Top Box, but runs off your home's internet connection instead of the COAX.