Does 'boxing in' the receiver affect the detection range of the remote control?
It depends on the material which the receiver is positioned behind. Wood for example does not affect the detection range, however metal will reduce the detection range to a degree. The detection range will also be affected if enclosed within a wall.
How many sensors can be used on one driver?
Sensors do not have their own wattage, therefore any amount of sensors can be used until they fill up the ports of the driver. The amount of lights that can be used on one driver is dependant upon the wattage of the lights and the wattage of the driver. To work out how many lights can be used on one driver divide the wattage of the driver by the wattage of the lights. A 24W (12V) driver used with the sensor will be maxed out one 24W has been used up.