I don't think Trump knows or cares what Republican party policy is, and executive power has grown exponentially in the past two presidencies (Obama and Bush 2). The Republican party already let Trump loose by purposefully courting white supremacists since the Nixon administration (example: Reagan's first speech was in a town that was famous for the brutal murder of three civil rights workers by the KKK in cooperation with local law enforcement in the 1960s: for more info, look up Chaney, Goodman and Schwerner
https://en.wikipedia.org/wiki/Mississip ... 27_murders )
If you're asking me whether I trust Republicans to be a check on Trump, the answer is no. I do not trust them. I do not trust them even a tiny little bit. They were not able to control him during the campaign, they will not be able to control him in the Oval Office.
If you still don't understand what Trump can and cannot do in office, perhaps this Fresh Air interview might clear things up a bit:
http://www.npr.org/2016/11/15/502157875 ... ke-of-a-pe
Edit:
Also, if entertaining videos are more your thing (they are mine) try watching the School House Rock classic "I'm Just a Bill"
https://www.youtube.com/watch?v=tyeJ55o3El0 and then the Capitol Hill Cold Open from SNL
https://www.youtube.com/watch?v=JUDSeb2zHQ0
(And it might be helpful to read back in this thread a little. The conversation is often heated and very much shaped by mine and saiyouri's personal views, but even still this thread is basically a blow-by-blow record of the election going back to last March. We spend a lot of time discussing whether or not Trump would be able to carry out the things he said he would do on the campaign trail)