I also found the issue with the "zoom" going into training mode vs. mission. Here is what I did to fix it. (Note that I use Track IR, so I dont have issues with panning around the inside of the cockpit with the mouse.)
1. For some reason when in training mode, everything works as expected. When you switch to mission mode, you lose the crosshair, get the radar blob (top right corner) and red text for cannon (lower right corner of the screen). I found that you have to goto OPTIONS, GAMEPLAY and select SIMULATOR (from the bottom of the screen). For some reason, the default is set to game not simulator. That will bring things back to normal "simulator" mode.
2. I also found that once your in the cockpit during a mission, you might lose the zoom in/out (w/mouse scroll) feature when viewing exterior of the KA-50 and then going back to cockpit. By hitting escape (to exit the game) and escape again (to re-enter), you regain the zoom in/out feature (or as JG14 stated alt c). This seems to be a bug, so hopefully it can be resolved.
Hope this helps!