Just of the top of my head:
1) average USD$1000;
2) Not sure. Grades are getting lower, and there has been no big discoveries for quite some time;
3). There is no 發改委 for gold price. The 發改委 is for gold's function. BIS maybe.
There are forces meddling in the gold market, but no central authority as such who can dictate gold price over the long term. "London Gold Pool" comes into mind.
The BIS perhaps is the highest authority in terms of gold transfers/settlement between central banks.