2) Stock photos are meant to be edited. If JPEG works for these large photo agencies, it'll work without a problem for you.
An editing workflow that is only 8 bits is not sufficient for retaining the best processing. Converting to JPEG is a sacrifice. A large photo agency or not, editing a JPEG is non ideal. With the price of storage (i.e. cheap) these days it makes no sense for an end user to save only JPEGs of their hard work.
As for info on the web about, here's a good link referencing the problem with JPEG saving problem
The quality differences are more subtle with generational losses when compared to simply picking the wrong quality level (above), but by the 10'th generation, obvious blotching and color changes are occurring.http://www.steves-digicams.com/knowledg ... osses.html
To quote the above website's conclusion:
What's the Bottom Line?:
The JPEG image format offers a way to save images using less space, but with some loss in image quality. Typically, a first generation save will be almost as good as a lossless TIFF as long as you use quality levels close to the highest available. Some "die hards" claim that you should never use a camera in JPEG mode when you have TIFF or RAW available as an option, and one cannot argue that you get the best quality and best editing capability with TIFF or RAW when compared to JPEG. That said, JPEG is a perfectly valid format to use even when capturing images the first time in your camera, especially when memory space, shooting speed, or the ability to print images without post processing is important. Remember that JPEG's are processed and ready to view/print, whereas RAW images require post processing to "develop" the images from the raw data. This takes additional time and can complicate your shoot-to-print workflow. A first generation JPEG will offer quality comparable to any other final or ready-to-print format, however, cannot offer latitude for correcting exposure and other shooting issues like a RAW image or a 48 bit TIFF. Bottom line: choose what works for you, but be sure to take the pros/cons of each format into consideration.
Also, here's a related article on JPEG image processing and associated limitations:
http://www.luminous-landscape.com/tutor ... lies.shtml