These are great!

The straight line is what we so often use in perspective, and it's a strict discipline. If you can do it already, great! Within a year you will be working on ellipses like crazy, and you may be surprised at how they are related, not only to straight lines, but to right-angled straight lines.

haha! They're up there in the sky looking out for us.

They are both actually part of the rib cage. This model has a very wide arch to his ribcage, so you see it more than usual. This arch can be greatly exaggerated on men to make them look more masculine. It’s something that Frazetta did a lot on his figures.

Sketchfab has a lot of models that you can view on your browser too

Hi Daniel! Marshall will probably give you a better answer to this but I hope this helps in the meanwhile. All the parallel lines in your scene, converge to the red vanishing point on the horizon line (marked in blue) except for the edges of the box. Those edges converge to a different point on the horizon (marked in green). The reason for this is probably because a linear perspective system (such as 1 point, 2 point or 3 point perspective) assumes all objects in the scene are aligned perfectly at right angles to each other. In real life however, objects are rarely aligned perfectly in this way. Usually something is skewed or leaning one way or another. So the box is probably rotated a bit more towards the right than the other furniture, causing its edges to move to a different vanishing point. One way to handle this is to capture this imperfect alignment by converging the edges of the box to that different vanishing point. The difference, however, in alignment is so small that you could simply choose to ignore it and converge the edges of the box to the same vanishing point as everything else. Hope this helps!