To the title question: Yes, he should have to avoid war. Now, the last two chances are (1) an overthrow of the regime from within and (2) Saddam choosing the exile option at the last possible moment.

I skip the second question as too difficult for me.

A big YES to question 3 (numbered (2) in the first post). Close to 99 % of all UN resolutions do not even mention means to enforce them. Like with individual people, they simply start by saying "You shouldn't do that" and so on. Agreement expressed in more or less strong words is their only weapon, in most cases.

Article 94

1. Each Member of the United Nations undertakes to comply with the decision of the International Court of Justice in any case to which it is a party.

Well, a much stronger UN might consider enforcing that article.

Wolfgang

Wolfgang