Help with Betting Website - VueJS

I am learning VueJS by creating a a simple Betting Application whereby a user selects a player to score.

Here is the app on Code Pen

All seems to be well, except 3 things:

1. I want when I select first player from one game and select another player from another game, the order should remain the same on the betting slip when I decide to change the first player from the first game. i.e If I select Rooney, Ozil and Costa in the order, I want my slip to be Mata, Ozil, Costa when I decide to change the Man Utd player.
2. I want to get the player's game id without having to repeat myself like I have done on the above code.
3. Add a class to the selected player. (Change background color maybe )

Someone please.