Read what mr V himself said about the merchandise here
I'd like to add that those Vintersorg shirts in XL I got are not that large, I've seen shirts in that size that were much bigger.
Yes, size is such a relative thing. But it DOES matter. *ehem*
No, but I've had XL longsleeves which seemed like M to me. And XL ones which seemed like XXXL to me. No way of telling beforehand unless you can try them out in a store.