For awhile I thought you might be a confused American, but you're well into troll territory now. I've been arguing, for several days, that the Canadian system has one ultimate decision maker. The US System has hundreds. Whether these numbers are humans, hyper-intelligent ants, or your mother is irrelevant as the the question of how many of them there are.
As for Civics, you really need to graduate to the Seventh Grade. Treaties are binding, even if unratified, during a President's tenure. This is because Treaties that are ratified are only part of US Law to the extent that a) they are within the President's purview anyway (ie: he can decide to open or close border crossings himself), or b) Congress has passed a statute to enforce them. Which leads inevitably to c) if Bill Clinton signed the Kyoto Treaty, then anything in his purview governed by the Kyoto Treaty has to comply with the Kyoto Treaty; which is exactly the same effect as if it was ratified by the Senate but the House refused to pass the legislation changing US Statutory law to comply.
In the case of the Iran deal, since it's foreign policy it's all the President's decision. He's talking about lifting sanctions, and all Statutes authorizing sanctions include clauses saying the President can lift them under certain circumstances.
As for elected dictator, what do you think a Prime Minister is? The checks on his power are three-fold: 1) He can't make a law that breaks the Constitution, 2) he has to retain the confidence of Parliament, and 3) His Parliamentary majority is subject to reelection every five years. That's it. In some ways they're real checks (all Canadian PMs who have ever lost power have done so because a) they lost a confidence vote, or b) they lost an election), but it's pretty much the minimum checks you could have and still have a Democratic system. Yet somehow Canada is not a dystopian hellscape.
As for Congress's power, I'm not arguing they don't have the power to shut down the government. I'm arguing that their power -to shut down the government leads to a high-BS, extremely decentralized political system where the wealthy have a major advantage on normal people.
As for being erratic, you're the guy who keeps throwing sentences to the wall to see what will stick. My argument is the same as it has always been. If you think that the problem with our political system is the wealthy have too much power, that's really fucking hard to fix because a decentralized system with checks and balances designed into it for the sake of designing checks and balances into it is very easy for a wealthy person to manipulate and very difficult for a working class schlub to manipulate.