"of" in place of "have" certainly had to come from people mishearing/misunderstanding "ve." There's no other explanation.
The accident one is funny. I had to really think about when I'd use "on", and it's when I say something like: "he did it on accident." Which is wrong when I think about it, but I know I've said this countless times. I can only guess it grew from "an accident" like "it was an accident."
Even though "on"and "by" are the same length, "by" sounds like it takes too much effort to say. How weird.
It's becoming more common in English for people to say "whenever" when it should just be "when." It's like nails on a chalkboard when I hear it used wrong like that