The Kisch brothers certainly used a wagon to transport their photographic equipment, but I don't think there was any equivalent of Fenton's wondrous machine (which he had built in England and shipped to the Crimea). The difference is probably because of the advancing techniques, as you say, with Fenton having to expose and develop his wet plates pretty much when they were taken with salt prints made a little later. By 1879 the mass produced (relatively) carte de visit had become common and cheap which is why we find so many now. Back in the Crimea it would have been quite rare for ordinary soldiers to have photographs made - we see some daguerrotypes/tintypes/ and glass positives in fancy cases of course. By 1879 most sizeable towns had a photographic studio.