An audit does not preclude the release of one's tax returns, as the IRS itself has pointed out by now. Trump is the only major nominee in the last four decades who hasn't released these financial records.
Trump is wrong
No rule against it
Rarely are fact checks so easy. Trump has tweeted some variation of this several times. He's also called climate change a hoax on the stump and in interviews.
Check her numbers
Clinton did indeed say the Trans-Pacific Partnership "sets the gold standard in trade agreements." That was in November 2012 during a visit to Australia as U.S. Secretary of State.