Airline categories .... All I can assume they mean there is whether the airline is legend, low cost, charter, scheduled etc. and in terms of industry awareness, they might ask you something about what corporate strategies a certain airline from one (or more) of those categories might do to maintain or grow from their position in the market.
Also, the last post mentions a lot of the key responsibilities a FO has - also note the heirachy on the flight deck - I got a few questions on that. Know what sort of hours you might work, what flexibility will be expected, perhaps citing someone you know as a source of information for this who flies.