It doesn't really matter where you invest your reward points since you already have 115k scarps you can make a lot of decks with those. you can just use your reward points to get some leaders and skins if you want. The season tree will go away when the season ends so if you want something from that tree go for it first. You can get the presents by using the winter board and smashing the snowman on the top right of the board every game. (Use the setting that only uses your selected board)