But as far as Trump himself goes, he's not really a Republican. He is solely concerned with receiving praise and feeling tough. There is no master plan; that is really all there is to it.
Yes, he is. He may not have a particular devotion to an ideology you'd like to pretend defines the Republican Party, but the US electoral system structurally produces duopoly between parties too broad to have coherent ideology.
To put another way, if you averaged out the beliefs of all who consider themselves Republicans, Trump himself doesn't believe most of it, certainly not dogmatically.
I think dragonwriter's point is that this is also true of most (many?) other Republicans.