I don't know, but the ratio will be much higher when judged by others than with self-identification. No one considers himself an ideologue. Also, people on the right (left) are more likely to identify people on the left (right) as ideologues.
It depends. Are we discussing Rust? Microservices? Or Climate Change? Other topics attract fewer flies.
1:1, as in, every commentator is both. And we usually don't know which we are.
Issue dependent.
Instead of trying to argue for the point, take it from a point of view of trying to be a teacher and everyone reading your post is a student.
Only ideologues are going to demand phd thesis levels of sourcing for an anonymous forum; but if you source well enough... this ratio becomes unimportant.