Geography prevents most people from exerting the form of control Iran has. It would be much more difficult for, say, Canada to control it. The Iranian coastline is pretty favorable.

Also, most governments are more susceptible to being bombed than Iran. They’ve been preparing for it for decades. If nearly any country (except for maybe a couple of Irans neighbors) tried, they’d be easily routed.

Yes. The US is already increasing exports from the Gulf and UAE broke with OPEC to increase the throughput of Fujairah. If Gulf countries start exporting through Fujairah or other ports, it's eventually game over for Iran.

The straight was open until the US/Israel attacked Iran without reason (and by bombing an elementary school full of girls).