No, hes not (the most dangerous man in the world). The president isnt a king. If he tried to implement those policies (and yes, if elected he would at least try), he just wouldn't get them funded. Democrats wont go for it, and neither will most republicans. If he wins (and i do think its very possible) hes going to find himself in position where the people who are supposed to be his allies in congress, the GOP, are mostly afraid hes going to destory the party for good.
One of the things you have to remember about trump is when we talk about a president and his mandate and what he can get done, we're assuming that he at least has some of his party in congress and in the leadership behind him. With no friends on either side of the aisle, there isn't a ton he can do. I don't think theres anyone in modern history you can even compare trump to in terms of how little actual support the party nominee would have from his own party in congrees if elected. Maybe mcgovern or goldwater.... but even they had at least a vocal minority of the party power structure behind them... and the rest was willing to set aside differences after the convention.
If trump gets elected, hell be the weakest, most ineffectual president in history.