how much gold?

Pardon my ignorance, but I have a couple
of questions, if anyone has the time...

How much gold is there (already mined) on the
planet?

Is there enough gold available to honour
the traded derivatives linked to gold?

Do any countries hoard gold on the sly?

Is it true that the long term average value
per troy ounce is roughly equal to (in australia)
one weeks average wage (since late 1800's)?

Do any states or regimes control gold mines
directly and secretly (in terms of how much they produce?

Can a gold coin (as currency) ever be worth more
cash than it's weight in gold?