well, I have to admit, Studebaker is one ugly looking truck.. but the model is nicely done.
as for the shields, there are hinges on top of them, so I guess it should be possible to open them.. and I don't think we'll see the Kate on Zis-5, it is just a different platform for the same weapon and it was replaced by this one later in the war which is the current focus of the devs regarding EF