Great point about watching the backcast. I often start a newbie off by doing side to side "pendulum" motions just to get the accelerate/stop cadence down. But you don't want to do it for long to avoid muscle memory.
For increased visibility of the backcast, an open stance with the opposite foot forward also helps aid the view.
Change of color is being adopted by more line manufacturers in the seasons to come, thankfully! This includes Rio, Wulff, Airflo for starters that I know of, some of whom already had it even for floating and intermediate lines.