Squat thrusts are in the chest section of PH in a modified version.
To do then: from a standing position, squat down low to touch the floor (you're now in somewhat of a "frog jump" position), jump back until you are in a plank position, jump back to "frog" position, then stand up.
Squat thrust climbers are in Boot Camp.
They are the same as squat thrusts, but add a vertical jump after you stand up.
Walking lunges are just doing alternating front lunges without returning to the starting position after each one. Just keep on walking forward! If you don't have the room for all 200 or whatever (by walking around a track or around your house), you can do as many as you can in one direction (down a hallway, for example), then turn and go back. Or don't turn and do reverse lunges (that's MY special tweek). If your space is even more limited, you might end up doing only 2 or 4 lunges forward before reversing. Just make sure that if the number of lunges is uneven (3 forward, for example), you turn and start with the other leg on the way back to keep things even.