My dad died in Minnesota in August 2014. My younger brother is executor, and seems fraudulent. What can I do?

My dad's estate was a large one, and he was a Florida resident for tax purposes, but died in Minnesota, in his "summer" home. My younger brother, as executor, lives in California (as do I) and inherited the lion's share, more than my older brother and I combined. He is paying himself $150/hr to deal with "estate issues" and flying himself first class between CA and MN, at $1000/pop. He is currently sitting on a huge chunk of cash, which should be distributed among the 3 of us siblings. But he claims he's hanging onto it in case the IRS decides my dad's personal and estate tax returns were done incorrectly and we have to pay more taxes. However, this gives my brother unlimited, ongoing access to the cash. It's been over a year since my dad died; seems like we should be done by now? Please advise - what can I do to force my brother to distribute the remaining cash? I'd also like to possibly sue him for recovery of the fees he's paid himself if they're excessive or fraudulent. Thank you!