Donald Trump is making promises that he can't easily keep. Between Congress and reality, pulling off what he wants to do will be quite difficult. To keep presidents in check, Congress has created quite a few balances to blunt the president.
For example, if you want to deport 1 million illegal immigrants, you first must find them. How many additional agents will that take? And then there's an existing deportation process. How long will that take? What happens when the holding facilities are full? At what point are you at capacity and unable to function? These are all solvable problem, but this will take time, money, and training. Literally, lawyers, guns, and money. In total, I figure another 100,000 government employees, at a cost of 20 billion dollars. Figure a year to build up, possibly two, before the program can even get rolling. Add to that the need to hire more judges to get through more cases. And then there's all the lawsuits about constitutionality.
What I see is a money pit.
I also see the Republican civil war continuing. What we have is one party in the Presidency and a different party in Congress. Their priorities are quite different. They will deal, but they will also clash. The easy stuff will go quickly, and then the real fights start. Everyone in DC knows that this is a power game, and they want that power. I expect and overall erosion of Presidential power when this is done as the House continues its ascendancy.