Assuming you’re referring to U.S. law, I’m not a lawyer, but if a character is in the public domain, they’re available for anyone to create new material with. Using the same list of characters in a different game/story that’s your own creation should be fine.

This may be unpopular, but the stalls are handicap accessible, not reserved.

I do try to be considerate. I keep time short and at work, where I am aware of where people who would have a greater need than I are located, then I go to the restroom they’re least likely to use.