Here's the thing. Actions speak louder than words. So the guy who said he had issues with the Civil Rights Act and voted against student loan relief isn't going to win over large amounts of African Americans and students just because he talks to them more than other members of his party. I think he'll make inroads with youth for sure, but it won't be as big as you make it sound. And they definitely wouldn't be anywhere near big enough to counteract Hillary's inroads with hawks.
Note that I'm not saying Rand couldn't beat Hillary, because he definitely could and is better suited to do it than most Republicans; I'm just saying that even if he does win, you won't see huge trends relative to what a standard Republican victory would look like.
Maybe, but Rand would at least do better against Hillary with youngs than Romney against Obama, and he certainly wouldn't do 10 points worse than Romney with Asians.
