Now that the primer has been applied, I can see where I really need to apply some extra care to get the right surface finish. The cracks in the corners will need to be filled with something (or maybe they could be highlighted to look like battle damage).
The two panels at the front are going to be painted before they get glued into the structure, because they'd be a bit tricky to access with a oaint brush once they're inside.
Regarding the hydraulic rams, there are two distinct schools of thought. One states that all surfaces should be primed and painted to ensure consistency of surface finish across the model. These are the kinds of people who often do incredible work with paint shafing to produce "non-metallic metal" effects (look up this technique on Cool-mini-or-not).
The other school of thought states that you'll never get a better representation of true materials than the original. These crafters use exposed metal or wood where these materials are to be depicted in the model. It may take a bit more effort to weather and fatigue to material in a "realistic manner", and there are quite a few materials which don't scale well (sometimes a thicker woodgrain just looks wrong on a small detailed piece of terrain). Getting the basics may be quick with this technique, but getting it wrong can just look tacky.
I typically follow the second school, but I try to push it from basic, through tacky... and on toward a more realistic representation. Sometimes I succeed, sometimes I find new ways not to do things.