Regarding the hidden traits we have this discussion going on for quite a while now. Basically since the EA launch :)
I can understand that people want all infos on the mercs, but if you can see all characteristics in advance we would have to balance all traits to make sure every man is evenly strong. Because otherwise the “bad” guys would never get hired and we could remove them from the game right away.
I dont enjoy that kind of min-maxing and I personally dont think the impact of the traits is so strong that someone becomes completely useless.
Its basically a design decision you have to take (similiar to the floating damage numbers issue) :)