As a sidenote to others, I've often heard the Shi'ites being characterized by others as the most radical Islamists by those who deal with Islam as "the Other,"
No doubt images of Ashura celebrations have something to do with it. For many who know nothing about Islam, that's the only thing that distinguishes Sunni Islam from the Shi'at 'Ali: The former are terrorists, the latter are sadomasochistic terrorists. Then there are those scary Iranians and Hizbullah who don't approve of the beacon of hope, peace and democracy that is our friend Israel.
You're right about ashura and unfortunately there are some shias who treat it as an entertainment session-- and go overboard, making a huge ritual out of it. It should really be a time of quiet reflection, not a 'raving' ritual fest.
About Israel, I can explain that aspect of it in another thread.
But just note that... in Iran, the ancient Persian empire is obv a huge part of the school curriculum. So they're taught the indisputable facts, that under the command of Cyrus the Great, the Persian empire helped free all the Jews from the Babylons and let them resettle in the land of Israel. Furthermore, the persians helped the Jews rebuild the temple of Solomon.
So the common consensus of the Iranian people, is that the Jews did resettle into their homeland, and did get their temple, and they did get the prophesied messiah-- which was Jesus.
However, after a series of droughts and earthquake, they've left that region for Europe-- and that's where the disagreement starts. Furthermore, the Iranians don't really agree with the notion of eretz yisrael -- where some israelis claim that the borders should cover all the oil fields in the persian gulf area- so this is another major area of disagreement.