No dedicated eReaders are in color yet however some are now 8 or 16 levels of gray so they can render fairly well. No dedicated readers advertize CBR or CBZ support although since these are really just RAR or zip archives some can read them if the extension is renamed although they will treat them as a collection of images, not a book. CBZ can be converted to eBook formats with a program called Calibre (see the section of this forum). I would expect that cbr and cbz are on the horizon for the near future. Ask again this time next year
Dale