I agree that Trump is useful, no matter how unreliable he may be as a candidate. Have you noticed that Cruz has become much more vocal on the subject of illegal immigration since Trump brought it to the forefront? He's also forced the pro-amnesty GOP candidates like Rubio and even Jeb to tone their pro-illegals rhetoric down, which may not be such a good thing because it gives them more of a chance to fool voters.
Not really.. Cruz has always been vocal about the border issue. He's just more cerebral in the presentation.