1) is about how 9/11 has changed international law.
The traditional law of self-defence - i.e. what it says in the UN Charter - is extremely narrow. It generally did not allow for pre-emptive self-defences. Note the importance of an "armed attack". Also note the difficulties associated with self-defence where the attack comes from a non-State entity, i.e. by terror.
After 9/11, the international community seemed to accept a much wider notion of self-defence. Support of the United States' actions and of its right to protect itself from terror was pretty unanimous, so some commentators argued that this created new customary international law, effectively widening the notion of self-defence in the UN Charter. However, this has somewhat declined in recent years, so the scope of self-defence is still very debatable.
So, you are evaluating how far 9/11 really did widen self-defence. An alternative tangent would be to argue that self-defence never was as restrictive as many thought even before 9/11, and that the post-9/11 situation was nothing unusual... but only do that if your understanding of self-defence is good.
2) has three seperate elements. First, whether intervention to prevent Human Rights violations is actually permitted. Its generally accepted that you can use force to prevent genocide, but its rather limited outside that example. Of course, what constitues genocide is up for debate - though in recent years some commentators have argued that the use of force is permissible in wider circumstances than just genocide. Second, whether the mechanism by which the use of force may be authorised by the Security Council is sufficient. This starts leading you down "the UN is a dinosaur and so noone gives a damn about the UN Charter anymore, its pointless when China and Russia have a veto" route. Third, whether allowing the use of force to prevent breaches of IHRs is a good idea.