taking the hinges off is easy as taking the bolt's out of them.. the problem is the bolts dont always like to come out nicely. make sure you have the correct size torx bit for the bolts and a good quality one at that. most common problem ppl have is stripping the torx's bolts ...so be carfull.
as for the stainless brakets....yes stainless will hold up better than normal chrome plating. but you still will be polishing alot to keep them shiny//and to prevent them from rusting.
as for the black stainless compared to the ''chrome'' stainless there is no differance.
alot of ppl will probally tell you not to put chrome on your jeep. BUT it is your jeep do what you like.
one more option is powdercoated hinges or just getting the hinges you have powdercoated.
with powdercoated hinges you dont have any maintnace such as polishing and such and the will most likely last longer than any of the paint on your jeep.