In the past I've used those on-camera devices to make prints from slides. They do work, but you have to be careful to get the right amount of light coming through. Diffuse light with a light reflecting on the white card is a good approach, more consistent than direct window light. (Or use the white card next to a window). For file format, TIFF is generally best, Bitmap is good, PNG is stable and very good but not used quite as universally (though it seems to be the file of choice for Macromedia).

For end-uses, after making and (usually) reducing a copy from your TIFF or PNG or Bitmap, GIF or JPG work. GIF is web-safe and uses just over 200 colors so it's good for stable web images if they're not complex renderings of colorful objects. JPG uses more colors, but depending on the monitor and browser, can display different from screen to screen. It's best to use a TIFF and save a smaller version to the gif or jpg format for web use. Just remember that every time you save a jpg file it does some averaging of the colors at the boundaries of objects in the image and this "lossy" format gradually reduces an image to a dull reflection of the original.

SRS