New at the game.

Hi everyone, I've started playing this game and wanted to know which class is the best/most overpowered. I've read a lot and watched videos, but they're quite old, and I don't know how things still are.

Besides that, the reason I started playing this game is because there are Krieg Death Korps skins, and they're my favorite faction in 40k. Is there any word on when they'll be coming to the shop?

Thanks everyone, and praise be to the God Emperor.