I was wondering. How does a Warg Marauder count towards the Bow Limit.
Does it count as 1 model with a bow, or does it count as 4 models (2 with bow and 2 without)?

Seeing how it only counts as one for all intents and purposes, surely it also only counts as one bow-armed model. It may have two shots per turn, but nowhere in the rules does it actually state the model consists of a warg, a shield armed goblin and two archers (then again, that's fairly irrelevant seeing how all the parts only ever exist together).

Ditto. Counts as 1.