Holy cow LS6 240Z!
Countersteering: The rider leans the bike by steering in the opposite direction from the turn. Going right, PUSH the right handlebar, the bike leans right and it goes right. Going left, PUSH the left handlebar, the bike leans left, and due to mysteries in its geometry it goes left. The handle push is an even and not jerky but quick motion. When you start from a stop the situation is muddied. It will steer like a car when going real slow but as soon as the bike hits a certain speed then it countersteers. You must develop a feel for that and the steering actually depends on how fast you accelerate from the stop.
You will notice when you brake this bike dives a lot. One of the big objectives on a sport bike is to use the throttle and brake as smoothly as possible so as to keep the bike level. That keeps traction on the front and rear even. That keeps you safer as well as the bike performing at its best.
Before braking make the bike perfectly straight. If it is leaned at all then inertia will want to throw the bike to the side and throw you right off.
Consider taking the MSF (Motorcycle Safety Foundation) course. Your buddy might be a great rider but the professional instructors are amazing at observing tiny nuances in the rider's use of front and rear brakes, throttle, etc. and they provide the best professional feedback. They have 200 CC bikes which are like bicycles to get around and best of all you can qualify for your motorcycle endorsement if you pass the exam after merely a couple days of intense skill practicing. The course is subsidized from license fees so they tend to be pretty cheap.