Regarding the chemical rounds found, reading the Iraq Survey Group's final report, (a)53 rounds were found and (b) the ISG thinks these were probably an accounting error. Hardly the reason to go to war...
to your first point, check out UN resolution 678 para 2.
Regarding your point that "there is some contention that 1441 did not specifically authorise war", well, if the UK and US and French ambassadors all interpret the resolution as NOT authorising war (i.e. no automaticity) then who are we to argue with them? Put it this way, I think the burden of proof is on those who wish to interpret 1441 as authorising use of force when already the main actors in this instance the UK and US already said publicly there's no embedded automaticity in resolution 1441.
Regarding your last point, firstly, you are shifting the goalposts. You initially claimed that the war was in accordance with UN resolution. You now make the point that, ok so the war wasn't in accordance with the UN...that makes them pansies. Different point.
But let's take your point as it is. What did the UN want Iraq to do? Get rid of its WMD and stop interfering with the inspection process. I recall distinctly by the time the war started (a) Iraq had already gotten rid of its WMD and (b) Iraq had let the UN inspectors go wherever they wanted. Which means Iraq had done exactly what the UN had requested. Which mean there was no need for "serious consequences". Thus the point whether the UN needed to back up what they said with action is quite moot since Iraq had already complied with what the UN wanted (no WMD and allowing inspections). So see -- the UN process worked quite well.
My third point is this: let's assume for the sake of argument that the UN had passed its resolution authorising military action on the (false) premise that Iraq still had WMD (based on the false intelligence provided by the US). Now assume the a UN coalition attacked Iraq and found
Thus spake the master programmer: "Time for you to leave." -- Geoffrey James, "The Tao of Programming"