About the missile, the closer to the center you hit the opponent base, the more destruction you cause, and the more chance you have of winning.
The score (Elo Rating) only changes at the end of the match and depends on whether you won, drew or lost, and also depends on the Elo ratings of each player before the match (your rating and your opponent's rating). The higher your opponent's Elo rating, when you win, your Rating goes up more points.
The Elo rating is used in Chess and Tennis to classify the players. (More info here: https://en.wikipedia.org/wiki/Elo_rating_system)
Thank you for the comment.