Nice start
Head is a little funky. But heads are in general. Humans have weird heads.
To answer your first question though your head is sort of tilted down, not terribly noticeable though. Might be because the anatomy is off as well though.
Rip cage is def to wide. Seems like you noticed it yourself which is good, I'm happy to verify.
Mandible is off because you didn't tilt the mandible with the rest of the head.
With his left forearm, I'm not really sure if we'd see a gap at all in the Ulna and Radius. While they are separate you'll notice that they move pretty parallel to each other, for us to see a noticeable gap in the skeleton the wrist would have to either be angled directly toward us or away from us. But I'd have to look at some refs to find out for sure. It is a tricky spot.
Everything else looks pretty good. Love the shoulders
Quickie edit