It knows who to send on the runs because if you are on the wings then any players running towards the box will rush forward and try to get into position for a header and if you are just dribbling in the center part of the field the closest player to you will break off straight to the goal for you to pass to them. This helps in defense when you are being hassled and want to pass forward and on offense when you want to pass to someone through the defensive back line.
Your honestly better off using regular crosses and low crosses (double tapping the cross button) because to me using the lobbed through balls only works when trying to hit it over everyone's head in midfield and having a forward try and outrun the defense. It doesn't really matter if you are running towards the box or touchline when hitting crosses, more that they have a good cross rating and are using their preferred foot to hit the ball (although heading rating and height of your target player will matter more in the long run).
no because whichever button you press should determine how the target will react to the pass, regular pass will make them just try to stop it unless you push either analog stick to continue running or knock it on while through pass will have him run onto the ball and keeps him from stopping (which will happen briefly with regular pass).
If you are ping pong passing or tapping the pass button the ball loses speed because players are just connecting with the ball instead of actually getting their leg into it. Either take control of your target or hold the button down longer. First-touch (if it is what I think you are referring to) is also called knock on which is when the player flicks the ball forward the second he gets the ball so that he can speed past a player, you knock on the ball the same way you kick it a little bit ahead of you while sprinting.