well, that's the big question, tigerlily. No, Saddam wasn't behind al-Qaeda or 9/11. But he did have oil. Even the previous head of the Federal Reserve (the US equivalent of the Bank of England) has just admitted that oil was the reason. The US should have stayed away from Iraq, and concentrated on sorting Afghanistan out; I believe they could have done it.
Not only did the Americans not help against the IRA, it was to a large extent American money that funded the IRA - sentimental Irish-Americans donating to a cause from the old country. It wasn't till after 9/11 that Washington finally noticed that the IRA were a terror organisation too and cracked down on it. Result: a peace deal.