1) They knew it already. Nothing to see here. Iran was always the outcast on the Persian Gulf, being Shiite, anti-monarchist and Non-Arabian.
2) That's the whole point. Iran shows that you can do damage cheaply, and very expensive to defend against, even against an enemy with far superior firepower.
3) It was before, and like Hamas, it is so deeply rooted in society that you have to kill the population, e.g. commit genocide to get it out.
Why should China and North Korea come out in support? Do they gain anything from their verbal support? As long as China gets its oil from Iran (which it does, and cheaper than other countries), it just sits and waits. And North Korea could not care less for Iran, but grins broadly because the U.S. is wasting money and military power somewhere else.
Your whole idea how the world works is very simplistic and in a black-and-white, us-versus-them scheme.