New player needing info

For the past few days I have been looking into purchasing a starter set of world of tanks. Amongst all the information I find online ,with all the wave releases I'm finding it difficult to find which wave was the cutoff for world war II tanks. Also I'm really curious as to how the scenarios play out in this game. Are there any match play rules or is it a simple skirmish game? Is there going to be any kind of additional supplements released in the future for matches? I'm not a very competitive person, but I like to have a structured game favorably with some kind of adjective or goal.