I wonder if the Iranians think less of Sen. Cotton (R-AR) since he thought to educate them on our system that they aren't educated enough to figure us out!. But the letter to Iran brings up some fun review facts for US government and if you are teaching AP Comparative, a way to tie it all together. For example you can mention the Supreme Leader as opposed to President Rafsanjani - another person we can assume received the letter.
But the letter refers, but doesn't mention executive orders. It is important to look at this chart to compare different presidents and the number they issued. Obama, for example, is well behind the pace of W. Bush. It is also worth nothing that Reagan issued an executive order dealing with Iran as well - this one lifting sanctions when our hostages were released in 1981. This is worth noting since it comes on a similar action by Obama agains the same country. Executive orders can be overturned by new presidents and never require the senate's approve as opposed to when treaties are made. But if the agreement is working when the next president comes in, it would be hard to get ride of it.
By the way, for all the Democrats criticizing Cotton, Nancy Pelosi did travel to Syria when Bush was president and was attacked for undermining Bush.