Ok, about the bathroom thing: First, we don't know if the alien races have genitals and/or an anus, but I'm gessing all the races (including humans) who eat solid or liquid food let their digested excrements to come out of some hole thing. So they would have this pipe, with different sized attachments. You would pick one that would somehow fit your uh... hole, and attach it to the pipe. It would suck out all the excrement. Then, when you're done, water would flow out of it, cleaning the area.

Or maybe they are just filthy people, and do it anywhere, and let the robots clean it.

And I'm almost sure Vader wears adult diapers.