Here is a more accurate answer:
The number of pictures that can be stored depends on;
The resolution (CCD ppi) of your cameras - Higher resolution images produce larger files.
The setting on your camera - fine/normal/hi-res.
The type of image compression used on your camera.
The subject you are photographing - If your camera uses compression the amount of detail in a picture will affect the final file size. Compare a picture of a car with a white background and a picture of a car in front of a forest.
Go here to find how many pictures will fit usning different size cards (megs) and cameras shooting at different resolutions (megapixels)
As for difference between SD & MMC is basically the size and type made by manufactor. I think you can buy SD cards that are larger in size (mb wise).
I will assume that your new camera is of the Kodak variety as most Kodaks use both type cards.
A good resolution depends on what you plan to do with the picture. If you are printing then 3 meg and above depending on size of photo. If you are emailing then below 3 meg is ok.