Figured I'd reply. Trying to build rapport on this site. I'm no game developer extra-ordinaire but I'm a writer who happens to code stuff on the side.
1: Just me. Depends on the project. Sometime's it's me and a close friend but for my projects on this account it's just me.
2: Yeah as I said in No. 1. I don't know anyone personally who is using AI and I don't think anyone SHOULD be using AI for their development. Period.
3: Well if it's me and a friend we split it 50/50. We don't have an LLC or anything (which is a good idea and you should do that but we're jackasses) so if it ever got any profit I assume we'd split the earnings evenly.
4: If it's me and a friend we would usually refuse to get anywhere until we agree. But we usually follow the same mental wavelength so we avoid tough problems like this. My advice to anyone trying to lead a project with someone else is to ALWAYS be close friends with that person. If you both understand each other you understand the ideas, and you understand their thought processes. It's easier for them to make compromises because you trust each other. And it can save time by avoiding arguments and creative differences.