Martin, thanks for the plug
Those shots were taken with a C700, not a C720, but it ois fairly similar.
One advice I give is to keep the ISO as low as possible, high ISO = lot of grain.
Also, you still need to have a certain ammount of light. Plus not enough light = difficulty to focus, and might cause those dots.
As for dead pixels, I don't think it is the case. There are always a few dead pixels (I have 4 or 5 on my C700), but it is not "all over"