Your info are very accurate base on my research. Just clarify few things:
1) CIS still need to wait for PD to process your GC even if your NC cleared long time ago. So it makes no sense to check for NC status if your PD is not current.
2) If your PD is current for 2-3 months ( give CIS some time to process), for my knowledge, you are sure stuck in NC which send to FBI long time ago. ( If you call CIS 1-800 numner and ask for trace, you will get letter telling you either 'We are currenly processing your case, due to additional information required, your case will take longer time to process' or 'Your case is dealayed due to security check.)
3) There are two ways to get the actual status of your case after its PD is current. a) ask help from the senator ( Not all senators is willing to do that now. ). b) play trick to get your 1-800 call route to the center processing your case ( or schedule InfoPass). ( Only 50% chane the person who took the phone will tell your the details of your case - like NC status, FP status etc. )
4) If you knew you are stuck in NC, You have no sure things can do to make it clear, just pray. Or may try few things I mentioned in my previous post.
Good luck for all the person who stuck in NC, we are in deep dark now, and hope more and more law suits can bring attentions to the top officers of the problems.