Fat that surrounds/lines your organs is kind of a different story than regular body fat. Organ fat is a necessary part of body function, so it usually maintains a decent composition despite fat loss in other areas, such as arms, legs, abs, etc.
However, the ratio of organ fat does decrease as total body fat decreases, it just decreases in small amounts. This is ok, though, because the padding around your organs is very much unrelated to other body fat and will not affect outward appearance. An excess of organ fat will provide health risks, but will not necessarily be noticeable when you look in the mirror.
My guess on your "barell-chestedness" is that it is simply how your ribcage has formed and it's probably due to genetics.
DAMN GENETICS!!! The one thing none of us can control!
I have somewhat a similar situation and was told by my doctor that I have "Pectus Excavatum", which makes my two lower rows of ribs stick out a little farther than the others. But I would suggest building your shoulders and arms to offset your chest and just make it seem like you've got a massive torso. Good luck!!
---Mr. S---