Question 1: How can I improve my control when sparring?
In two words, practice and experience! To have good control, practice using good control. The first time you tried to touch your nose as a baby, you probably poked yourself in the eye. Now you can do it with the slightest touch, even in the dark or with your eyes closed.
Sport Taekwondo does not train for control as much as does traditional Taekwondo, so most sport students do not have much control. If you train for control, you may hit soft, or hit hard; whereas, if you only train to hit hard, you will have difficulty hitting soft.
To get better control, train everyday on a heavy bag striking with punches and kicks. Strike with full power and speed, but only touch the bag. Practice while moving and while using combinations. Stay relaxed as if you were a marionette being held up by strings and would collapse in a pile on the floor if the strings were released. As you move about your house, strike at various objects with focus and control (be careful however, I have broken various things, including my hands, while doing this in the past). Consider a perfect technique as one that is perfectly formed, is delivered with power and speed, and which stops at a precise point in space.
Plains Indians considered being touched with a coup stick during battle to be a fate worse than being bashed with a tomahawk. Opponents respect perfectly executed techniques that, although did not touch them, could have harmed them if you had so desired.