Ceiling Fan j-box already has 4 wires (black, red, white & ground), do I still need to put the receiver in the canopy if using the Fan/Light Switch? Or can I skip the canopy and just install the switch in the wall?
Yes, you need the canopy module. The switch communicates with the canopy module via RF. The conductors between the switch box and the fan are just used to send a constant hot to the fan to power the canopy module.