The hear in front of the flywheel should move freely. That's your clutchbell/pinion gear. It's driven by a centrifugal clutch attached to the flywheel.
Your throttle servo moves the brake linkage, activating the brakes. When you push forward on the trigger, the servo rotates the opposite way...
That response deal is your reciever. I don't know UK sellers, as I'm across the water. I personally really like Savox servos and I hear a lot of good things about Spektrum radios. Also hear great things about Hitec, Airtronics, and Futaba. And I would ditch that 4 AA holder for a rechargeable...