If it’s not a secret, what is the main expenditure item while developing of the role-playing game?

If by expenditure item you mean resources, I'd say marketing, and from at least one of our most recent RPGs, the marketing outstripped the cost of developing the project several times over.

What biggest failure in RPG genre could you recollect?

Lack of balance is the great destroyer, and while it's been in a number of recent titles, it's not a recent development. Lack of combat balance and any need for tactics - so much so that the combats are so easy that you don't have to do much to win or vary your combat style - is pretty crippling. One RPG in the past I've never played because I'm aware there's one low-level spell that makes the critical choice with your character progression in the game meaningless because that spell is overpowered.

Also, I feel combat mechanics are neglected in a lot of current titles except Kingdoms of Amalur Reckoning. KoA's combat felt very fluid and it felt like they'd put a lot of care and attention into its mechanics.

How much time does take from the moment of the first idea till the story outline writing? When do the game-designers start their work, how is further cooperation of the group built with the material written? On which stage is the ready scenario with dialogues and scenes enriched?

The publisher pitches we do require that we have a story outline (at least a page or two) when we submit the pitch. That can take 1-2 weeks, and then we build from there. Over the next 3-4 months the Creative Lead helps flesh out the areas, major NPCs, companions, etc., vets it with the other Leads, and then when the game enters full production (usually after vertical slice), the narrative tasks are divided up or, for a smaller title, the Creative Lead does all the major scripting for the title.

Have you got congenial developers who have the same idea and point of view on game industry? If you had a possibility of joint game project who of your colleagues could become a perfect co-author?

I've worked with a number of great developers. Some I currently work with and others I'd work with again: Dan Spitzley and Brian Menze (we've been together since Torment), Tim Donley (lead artist on Torment), George Ziets, Anthony Davis, Tony Evans, Travis Stout, Colin McComb, and Tim Cain. I'd work with Ken Levine in a heartbeat, but he's already got all his story stuff handled, so he wouldn't need me. I like David Gaider a lot and I think he's pretty sharp, I'd work with him. And Mary DeMarle. And Richard Dansky. As for Brian Fargo, I'm already working with him again on Wasteland 2. : )​