The states don't send the fed money. Federal taxes are paid by individuals directly to the IRS. There is no current mechanism for the states to intervene.
Yep we will. See there is a big difference for a wannabe dictator constrained by the law and separation of powers, and an actual dictator who has consolidated power.
How will Trump stop the midterms? The feds don't run elections, the states do. He lacks the manpower to declare martial law across the country and occupy polling places.