not sure about the channel thing, my TV has AV so the DVD is in AV1 my recorder is in AV2 etc. but is you have spare red,white and yellow on your TV it should work. I think one control comes with it but you can buy more, you need two controls for most games. We don't have the dance game but I have seen it being played on a morning show here in Australia, it think you just copy the moves and you get points, not sure?
The WII fit takes your BMI and sets an exercise programme for you. We have one but it is my Grandsons so I do not use it very offen. The WII has a sensor that pick up the signal from the controller. Not sure is I have been helpfull probably confussed you.

all the best

Lesley