1, He certainly acted like the “star” – after all, he’s better known as a television celebrity as anything else. “Star” doesn’t mean “winner” – in fact he was the “bad guy” in his TV series.
2. If he turns out not to be as conservative as first believed, his third party threat is more credible in terms of winning, but less of a threat for the Republicans. The reason is that instead of being a “extremist” appealing to “true believers” (cf. Pat Buchanan and Ralph Nader in 2000), he would be a moderate running against the “extremists” of the “Tea Party” and the “Occupy Wall Street.”
3. While he is very anti-PC and racist, most of hie other views are not so radical, and he’s been a big advocate of corporate welfare in the past, and a frequent support of liberal Democrats.