The idea that there were WMDs in development / ready to use at the drop of a hat was part of the motivation to go to war at the decision-maker level, but not the core reason, I think. It was more a "look out, he has a gun - rush him" kind of snow-job to get in there, with the idea that something could be found to justify that approach.

The bigger idea was a domino concept; that a remade Iraq would be a beacon of democracy in the Middle East, that all the other states would similarly switch over (one way or another) to democracy, Muslim fundamentalism would no longer be a threat, and the whole region would be a capitalist wonderland with oil. Sort of like 50s/60s communism in reverse. But it didn't quite work out.

Yes. Tons of evidence there were no bio weapons in Iraq. The UN weapons inspectors had inspected every square inch of Iraq over and over again. They said there was nothing to be found.

Biological weapons are easy to make. Remember Aum Shinrikyo in Japan in the 90s? Or Jonestown? It would be a fair assumption that half the world's militaries have some sort of biological weapons. Granted, many of them won't be able to put them on missiles and launch them.

So claiming that the presence of bio-weapons in Iraq is some sort of a justification for invasion is just plain silly. If this was all that was needed, we would have invaded half the countries on this planet; many of them continue to be far worse than Iraq ever was.