Which things would i be able to exchange, and which Rocket League Items not? 

You can exchange uncovered Blueprints, things worked from Blueprints, free Dropd, credits, Pro and Free level Rocket Pass things, and occasion things. You can't exchange concealed Blueprints, things purchased from the in-game shop, extra presents, Esports Shop things, DLC things, normal things, Premium level Rocket Pass things, and serious season rewards. Credits likewise can't be exchanged to no end. 

What packs are there in www.lolga.com Rocket League?