How Good are you at Modern Warfare/Spec Ops

Do ya Pwn, Own, are you good, or do you suck

1 What lv do you unlock the AK-47
2 How do you get past a Riot sheild
3 What does the "Nuke" do (I once got it!)
4 Haertbeat sensor= Pwnage?
5 What is the max amount of stars in Spec Ops? ( NOT how much you can earn)
6 Do you like Spec Ops?
7 Do you have a Microphone?