Welcome aboard!
I have no opinion on the traction control. Mine kicked in once when I was turning a wet corner and had to step on the gas a bit due to traffic. I don't think having it on hurts performance or economy in any way.
Perhaps more so than the other hybrids due to the power, the HAH reward a light foot. When I'm using that V6 power (or, more often, the wife is

), we see mid to high 20's. With a light foot I get high 30's to just above 40.
As for running on only 3 cylinders, that is known as Eco mode. There is a green (of course

) light that says ECO that will turn on. This is the key to great mileage on the highway. When I drove my car from the dealer in Shreveport, LA to D-FW, Texas I got about 36 MPG at between 75 and 80 using Eco mode. I am about to take a 1500 mile round trip, so I'm hoping for even better this time.