I’m not unlocking anything

The game uses quite a realistic physics engine. The ball is modelled as a sphere (roughly) and each car has a cuboid hitbox of slightly different dimensions. Therefore things like the tilt in a dodge or an aerial (using air roll) alters the trajectory of the ball after impact. Spin does affect the ball when travelling through the air as it curves towards the direction of spin but not when travelling along the ground (at least not noticeably). Obviously the angle at which you hit the ball is going to have the most effect on its trajectory. Collisions in the game are purely Newtonian and momentum based so boosting and driving at the same speed will have the same effect on the ball.

On a gameplay level, its best just to go in to free play and get use to the mechanics of the game instinctively so that you can judge what your touches will do to the ball.

EDIT: Without a proper picture, it will be very difficult to guess which award you are talking about. In any case, you can view all of these awards in game from the main menu under Extras -> Stats. Scroll through all of them until you find the symbol you are talking about.

The only thing that comes to mind is this symbol (top right, bottom of the stack):

If so, that is the Playmakers Award, which is earned for every 3 assists in a single game.