[analog31]

On the research point, why are research and teaching commingled?

They aren't. To an ever increasing extent, undergraduate teaching is done by adjunct staff, who are not involved in research, and who work on a temporary basis.

Professors with good research funding can often buy themselves out of all or part of their teaching load. Many choose to teach only the upper level or graduate courses, where immersion in research is in fact a useful qualification for teaching.

Disclosure: I was an adjunct for one semester, many years ago.