Your first case is possible at some but not all US universities. There are many whose primary mission is teaching with only minor research responsibilities. The usual way it is put is that you "need to keep up with the field". But at many other universities, research is a major part of any tenure decision.
Your second scenario is probably much less likely. The titles you give often don't come with tenure, though in some top level places, Research Scientist would be more likely to be tenurable. But even then, some guidance of graduate students (i.e. "teaching") might be part of the job and evaluated in any tenure decision.
I'll note that at some very fine institutions (CMU, Duke, Stanford, ...) there is a special track for teaching faculty (Professor of the Practice is a common title) and these positions, while not tenurable, come with, say, renewable ten year contracts. But they also have high standards both for teaching and for "keeping up". In this case, keeping up usually means that you also publish, though publishing pedagogical work rather than strictly scientific work is probably mostly the norm. People that I know in these positions either have doctorates or some other outstanding qualifications as educators. The positions are very secure, even if not tenure, strictly speaking. (Information here supplied by a Duke PoP).