This depends entirely upon the format used. Most photo cameras will make pictures in JPEG format (modern ones). A very large, high quality JPEG will take around 500 Kb. 80 Gb has 80.000.000 Kb in it. This means it can comfortably contain 16000 pictures. Larger (example: Photoshop) files will take around 5 Mb (again, quite large). This is 5000 Kb. You can store around 1600 of these. Let's just say most private users will never fill them completely with pictures.
80,000
80gb
80gb
sd card
Yes
photos
Ipod touch 8gb because you get to get apps, go to the Internet, take photos and videos and many more stuff you can do, which isn't available on Ipod classic
If your photos and videos are stored on iTunes then they can be retrieved on another device.
20,000.
Pictures taken in Nintendogs + Cats can only be stored on the SD card. The 3DS does not support saving photos to internal storage.
Roughly 6 photos. Get a memory card.
Photo hosting is a service offered by many websites. Users can upload photos to the website where it will be stored other people can view it. Many companies also provide print services for photos uploaded to their websites.