For the riding -- try sitting with your pelvis tilted back a little and feel as if you're sitting just behind the motion. If you keep good contact with your hands, the horse should feel you behind the motion and holding the mouth and slow to the pace you want.

Oh, and hold really tight with your thighs and knees. I had an instructor who used to fold up a kleenex and put it between my knee and the saddle (stirrupless English) and if it fell, I wasn't holding on right. Have they made you post without stirrups yet? *g*