President Donald Trump's zeal to unveil a tax plan before his 100th day in office is raising questions about just how thorough his "tax reform" plans will be, amid signals that his focus for now is on slashing tax rates.Trump has directed aides to move quickly on a plan to cut the corporate income tax rate to 15% from 35%, a Trump administration official said on Monday.With his 100th day nearing on April 29, Trump has been ordering studies and signing executive orders. But he has yet to introduce a major bill to the Republican-controlled Congress on any topic or win passage of someone else's that he supports.