There's no limit on how many classes you take and that includes the DoH and DoL ones.

Goldsmith is good for all classes as it provides accessories and it makes about a third of the weapons for pugilist/monk. The others are made by blacksmith and most of your armour is going to be made by leatherworker and weaver, with the odd piece made by armourer.

That said crafted gear is currently "nice but not required" so I would only recommend getting heavily into it if you enjoy the crafting minigame, otherwise you may not find it worth your while. While it's possible to make money at it crafting isn't the money-earner in this game that it is in other MMORPGs.