Well Young Scholar how long do you think it would have taken to put the WMD pieces together? Clearly there was the will and there was the infrastructure and the wealth. How long can any nation seriously deter a nation without taking any credible action? Oil for food demonstrated the folly of "pretend" deterence. As for building democracy, we did it in Germany, Japan, South Korea, the Phillepeans and to a certain extent Taiwan - it took a long time and a lot of money. We failed in South Vietnam and are on the verge of failing in Iraq. I believe we are safer for our efforts. I don't fear Germany, Japan, South Korea and others will build and distribute WMD. I think it is more likely in places where thugs maintain power through murder and torture. I'd also hate to see a world where terrorism always trumps democracy because good men chose to do nothing or don't want to spend more than 3 years doing it. The world has grown just too small for me to ignore the murders and rapes in a neighbor's house. WMD may yet thin the heard and make that small world much bigger in the future...not that it's any of our business. ;-)
That's hard to say, and given what we believed at the time, there certainly were good reasons to invade.
As for building democracy, it has become a useful goal when we've been involved in countries for other reasons (for instance, Germany or Japan), but on its own I doubt many would consider it a good reason for significant military operations in a country. Since we're in Iraq already, we should ceratinly make every effort to promote a stable government, but the goal of a stable government wouldn't have alone provided a sufficient reason to enter the country in the first place.