Cheers, thanks very much for the answers, clears things right up for me.
Still a bit unsure as to why I would use Artillery. A 2/2 unit for 4 IPCs versus a 3/3 unit for 5. Artillery may support infantry but Tanks have got 2 move and Blitz, which more or less cancel each other out. Using Artillery as the Soviets to help Infantry take and hold WR or something along there makes sense, but other than that I don’t see why I would ever build them instead of tanks, as I’d have to invest a fairly hefty amount of IPCs to get a significant numerical advantage.
That being said, I’ve only had this game for a day or so, so I’m sure there’s something I could be missing out on.