1. The left-side Golem Guy (and the entire level, in fact) is really just there to demonstrate the mechanics of air tunnels. Specifically that you will shoot right through a perpendicular air tunnel unless you have a backstop of some sort. It is important that the player learn this in an easy level so they can be sure they understand the mechanic before moving onto more complicated levels that use that mechanic again. We've been working on a post-jam version and in that version you actually do need both Golem Guys.
2. I am kicking myself for not realizing that sooner. That level went through several revisions and somehow neither of us figured out that was possible. The intended solution to the puzzle is to ferry Person Guy to both boxes so he can push them.
3. I believe what you're referring to is purely a visual bug. I've fixed it in the post-jam version.

Thanks for the feedback!