A:Answer Yes, you can erase the photos on the card, but make sure you have your images on your hard drive and preferably, on a flash drive, too. You can never be too careful. I feel it is best to format the card IN THE CAMERA to insure reliability.
Will it affect the numbering system? Yes and no, it depends how you have your camera set up. If you have selected Continuous numbering, formatting will return you to #1 with most cameras. If it is important to you to keep the numbers sequential, then erase instead of formatting.
The size of the card has nothing to do with the clarity of the image.
