Also P.S. I have noticed that power adapter does not seem to be in stock anywhere. What are my options if I need a replacement
It's pretty safe to say the NC is beyond end-of-life as far as B&N is concerned. It was replaced by the NOOK Tablet, which has since been replaced by the HD/+ line. You can still get support from others here, and probably at your local B&N. Any warranty is presumably long since expired.
If you're feeling adventuresome, you can load a variety of alternate firmware, but don't set unrealistic expectations. The NC is an old device and won't peform like the newer ones can.
So far as a power supply replacement: Check online with Fry's Electronics. That's the last place I saw them, though that's been a couple of months now.
The key to fast charging is the B&N cable. The one with the illuminated 'n' allows charging in a few hours when combined with a high output (~2.1A) adapter like the stock B&N adapter. If your cable is the problem, you can charge at about 10% per hour with a conventional microUSB cord like the sort common for most phones these days provided you have a high output AC adapter for it. If you plug it in each evening, it should be ready by morning. Anything with lower output will charge slower. Charging off a computer USB port will barely work if the screen is on.
Are you having any particular problem with yours?