plowhog, if you get a cab you will fog up. It is how quickly, and how often. Get a demister, you will be well pleased you did.
hydraulics: you require 1 scv to extend the ram and a 2nd scv to make the ram retract, ie 1 pair per ram (this is double action). Most hydraulic impliments need double acting rams to work. If you get a medium duty 8' back blade that may be light enough that a manual model will work. Alternatively a box blade may be better for you. This means you would only need 2 pairs(4scv outlets).
My blade is a heavy duty 6' manual 3 way blade and is too heavy to adjust on the steep tracks I have, I need to go to a fairly level (15 degree slope) place to adjust the blade. Tractor was a mf135 7'6" wide.