Ok I can give you some basic tips, was once a c700uz owner. But I'd advise that you read the manual thoroughly, and search the web for answers to basic photography terms, and also to experiment more! Film is free anyway for your cam.
To do nightshots with c700uz, never use P or auto mode, not even shutter or aperture priority. In these modes, shutter speed is limited to 1/2s the most. In most nightshoot environment, you'll need longer shutter speed than that, so you must shoot in M mode. Also, P or auto mode will trigger auto ISO, that's why some of your nightshots are grainy cuz the camera decided to use higher ISO due to the low light condition.
So for nightshots, try the following tips:
1) use M mode
2) set ISO to 100
2) set aperture to f2.8 (if you don't mind no pristine sharpness)
3) set shutter speed to whatever the causes the EV scale on the top righthand corner to set to 0. Or better still, experiment with different shutter speeds and find your preference. Typically between 2 to 4s.
4) Set manual focus, focus to infinity if your subjects are all far away.
5) Use custom white balance (or 'one-touch' WB) on the scene
6) Take the shot using self-timer mode.
7) Off the camera until you are ready to take the next nightshot. This is to prevent further heating up of the CCD, which will lead to hot pixels.
Try these, see how it goes.