Newbie underworlds questions

[Durnaxe]

So I had never really considered this game at all when I first picked up AoS.
Well in our slow grow league I ended up winning a box of nightvault....in french.....I can't read french.....******.
Between Google Translate and other internet sources I'm sure the cards being in French wont be to much of an issue. While there is no gatherer like MTG I'm sure there are translations online somewhere.
My questions are going to be more tournament or event related. I tend to only play in those types of events because my close tabletop friends have a completely different way of playing games then I do (I like objectives and one on one games, they like no objectives and at least 5 ####ing people in the same game).

I'm not super interested in playing either faction from the box right away (eventually, except the sigmarines. Those may end up as kitbasing bait) but when I first got into AoS I picked up the Ironskull's boyz box, the one without the cards. Is there a way to get the cards separate?  Or would I up with two sets of mini's worth Ironskull's boyz if I want to play them? Am I allowed to proxy the specific cards to their box?
How does one actually obtain extra cards for their decks. Is it from the boxes only? So no booster pack like products? I haven't looked at deckbuilding since, ya know, my rulebook is in a language I can't read (FYI I live in the states. I blame the MTG community's fascination with alternate language cards for making ****** like this popular).

Thanks to anyone for any help on this.

[Skyeline]

Breaking it all down through the list of questions you asked:

1. Is there a way to get the (Ironskull's Boyz) cards separately?
Nope, unfortunately. You're going to end up with two sets of the Boyz unless you can find someone out there giving away the cards or listing them for sale somewhere.

2. Am I allowed to proxy the specific cards to their box?
You could probably get away with it if you're just playing with friends or casual pick up games if people are cool with it. Tournament wise though that's a no go. You need to have the actual Underworlds cards.

3. How do you get extra cards? Is it from boxes only? Are there booster packs?
Boxes only. There are some odd releases here and there which are cards only (Echoes of Glory and Leaders Pack). That being said, those aren't random booster packs and instead have specific cards in each box. Outside of those two, every other card is included with a specific warband or one of the two core sets.

You can always check out the Deck Builder on the official website and filter cards by Expansion to see what comes in each box. The only thing that isn't listed are the fighter cards themselves.