I don't know why anyone would insist on first, especially on QR. It is the best business class in the world, and is perfectly comfortable, even on long sectors. That's my feeling anyway.
As I said, First is a rarity, there will only be 13 A380s and First will be only for some select routes, the most popular ones such as LHR, CDG etc. QR also market the upper class of the A320s as first class when flying around the gulf, so there's only F or Y available on most flights in the GCC.
As for the kids, no matter who you are in the company children under 12 must fly in Economy.