Greetings! To answer your questions simply, we currently have no character artists on board, so I don't think editing a character model is currently possible.
Weapons running dry and the gun staying cocked back, that's actually a neat detail, I didn't notice it, but this is most likely possible.
As for single-player... The AI is absolutely not programmed for a single-player experience. At all. No guard animations and no proper guard models are done, we'd have to recode the entire damage system as far as I know to fit guard health limitations, we'd have to code proper guard behavior, guard routes, objectives, automated turrets, third-person cinematics, sky changing from day to night when second baron is defeated, all three difficulties accordingly, and a bunch of other stuff. As you can see, it's not as easy as you thought, and we don't have near enough team members to make this level alone happen in a reasonable timescale, or at all. I know everyone wants singleplayer done, but we have to be realistic.