In the Pe-2 cockpit, the pilot's seat sits on a raised platform (not a full floor, per se) on the left side. The gunner right behind him has a side-ways facing chair on the starboard side (facing port) and he stands up to aim the gun and turn the turret. The radio operator in the rear cabin also has the ventral gun. He can open some flaps to see out below him, and open some doors to aim the gun (I believe it's locked when the clamshell doors are shut). The radio room started with 2 guns on each side as well (the two small mushroom-shaped windows each had an SVak (spelling?) shooting out each side. However these were ineffective, heavy, and removed by ground crews almost immediately (and most of those windows were painted over with the camoflague). However, the ventral gun position, much like that of a Boston or A20G, most likely had more of a downward cone of fire, rather than a rear-ward cone of fire (it's nearly imposible to get on your belly to aim straight aft, let alone see past the clamshell doors at that angle).
Those diagrams show the internal bomb bays. However the more common bomb load was on 4 external bomb points under the wings and fuselage (blocking the bomb bays). I believe it consisted of 2 500lbs and 2 1000lbs bombs (it was 2 large near the center and 2 smaller outboard of those, so either 1000/500 or 500/250, which I don't buy, it's too light a load to be effective for anything).
It had 1 forward firing gun, a 12.7mm gun (as the ventral and dorsal guns were), and I believe it only had 150 rounds.
