A few of the details on the forward fuselage seem a bit off to me:
Here is a photo of the forward fuselage of KA-3B Bureau Number 142244 showing the location of the ATM exhaust ports and the aft end of the IFR fairing.
The questioned raised rectangles on the belly are associated with the bomb-bay anti-buffet fence. It proved necessary to keep the bombs from rattling around in the bomb bay after release rather than dropping cleanly away. It was normally, but not always, extended when the bomb bay doors were open.
Hopefully the Trumpeter kit includes a separate fence that fits over the raised rectangles.
Note also that the most outboard rectangular opening is there to expose the catapult hook well.
Here is a picture of the right side of a Bomber forward fuselage that illustrates a couple of nuances. It has both the early sextant opening on the right side of the canopy and the later "bubble" on the left side, which is not common. There are a couple of long narrow external patches on the lower side of the fuselage (the skin wrinkled noticeably there on the catapult stroke; you can see evidence of it here).
Compare the picture above with one of a TA-3B, which was a Version, the nickname give to non-bombers.
A comparison of the Bomber versus Version entry door thickness, location, and angle:
More later, maybe...