well first off before you remove any springs on either side do a quick diagram or take a few pictures of each side, so you know how the springs are all located as well as the adjustment pin.
and if you can take off the drums and take them to a shop that turns drums and rotors and have them test the drums to see if they are turnable OR if they must be replaced.
no need buying new ones if you dont have to! but i would replace both wheel cylinders and pads,springs all at once as well. at least that way YOU KNOW your rear brakes are all good and wont have to be messed with for along time!
i say both wheel cylinders since youll have to bleed the system anyways so might as well replace it at the same time since its so cheap!
hardest thing about doing rear brakes are those springs! they sell afew tools to make it alot easier.... but sometimes all ya need is a few different types of pliers or screwdrivers. just remember where all the springs go and youll do just fine. and only do one side at a time, so you do have a comparison by using the otherside.