Re: Browser support
JPEG2000 is now largely irrelevant due to the advances in image compression made by the video industry in h264, webp, and even more with the new UHD stuff*. But JPEG2000 didn't take off because it was encumbered in patents from the start.
*Mozilla recently ran a comparison of alternatives to JPEG: http://people.mozilla.org/~josh/lossy_compressed_image_study_october_2013/
WebP is my favourite at the moment because it also for lossless compression where required making it suitable for both photos and text. Just missing a "file-in-file" approach to handling responsive images.