Answer:
an attachment is below
Explanation:
1) the formula for damping coefficient id for RLC series circuit.
For \xi =0 you can make c=0 but inductor will still have some capacitance.
2) the responses of critically damped system and under damped system are shown with comments on their time response.
4) There can be many different answers to this question, but the 4 I have mentioned are the most important parameters we need to know about an unknown op-amp if we are to use it in our circuit.
Hope it answers all your questions.