ok, I'm not sure on the Economy racks, but every other AP product has a slot for your thermostat probe, so I assume that they do as well.
Unless you are breeding I wouldn't even bother with the night drop functionality.
As long as you don't have more than 350 watts then you don't need to worry about wattage (thats 17.5 feet of 11" flexwatt) all you do to figure it out as take the thermostats max wattage and divide by the Wattage per linear foot that the flexwatt is (11' = 20 watt per Linear foot, 3" comes in 6 watt and 10 watt versions, 4" is 8 watts)
did I cover everything?