Well, as I understand it, the empty warheads were such that they could be filled with just about anything, such as high explosive. It's a bit like saying a lorry container could be filled with chemical warfare ingredients; it would be quite true but not very meaningful.

The evidence so far seems to indicate that the artillery shell containing some Sarin was a junked one they'd retrieved. I imagine if they'd known it contained Sarin they might have used it in a more effective way.

As to why, if he'd got rid of all his WMDs, as he claimed to have, Saddam didn't allow unlimited access, there are several theories about that, aside from the one that he was lying. The two most plausible are that (a) he could see that there were plans for an invasion, and could have hoped that the invaders might be deterred if they thought he actually had an arsenal up his sleeve, and (b) that he knew that a lot of Iraqis didn't like him much, and if they realised that he hadn't actually got anything up his sleeve, they might take him out.

I think Saddam was a fool, but then that is a fairly common condition among heads of state. I think it's probably something to do with having their feet too far from the ground and their head in the clouds.

Once the invasion was in progress, it seemed evident to me then, as it does now, that his failure to use them demonstrated pretty conclusively that he hadn't got them to use.