You can make FPs as complex as you want to, as far as I know. I think past a certain point you're probably better off ending a FP and starting another, using the previous FP's resulting tags as a requirement -- because if you fail any mission in a FP, you fail the whole thing, and if you're 10 missions deep and you fail you're gonna be *really* angry.
Tips, um. Remember that people are only guaranteed to read conversations and interrupt dialogue in missions, so don't rely on the mission briefing text to convey story points. In fact, if the mission is consecutive drops, the only place the player will see the briefing is on the loading screen. i dunno about you but I mostly ignore the loading screen so I miss anything written there. Um, what else? You can give different reward packages for different endings, if you branch; check the rewards for the 'too moral to do this' exit from the Liao Alliance FP, for instance.
There is no character guide for the cast; you'll just need to pull their dialogue out of the existing material if you want to try to capture their 'tone'. I write Darius as a professional soldier, Yang as a brash and irreverent jerk, Sumire as enthusiastic, Farah as upbeat and academic. I don't write them exactly the same as Andrew, or the Events team; all of us have a very slightly different 'voice' for each of them. So as long as it feels right to you, you're probably within the scope of the character.
