Re: Calendar on NC
There is the tweak "Calendar for Lockscreen" which shows your calendar on lock screen.
In the settings you can customize a lot, for example which calendar, how many days, location, Icons etc.
It's not in the Notification Center, but on the Lockscreen, which is awesome, too.
For the NC there are no tweaks available which show the calendar. Tweaks/(Apps) which are probably able to do that are LockInfo and IntelliscreenX, but both of them aren't iOS7 compatible. The Devs are woking on a update, but it will take time... :/