The answer to your questions vary greatly from one geographic are to another. So, you are going to have to talk with people in the specific region you are interested in.
However ... in general ....
Some schools do hire people with only BSN's to teach undergraduate clinical courses. In particular, LPN programs and ADN programs often do not require an MSN. Some BSN programs do as well, but most universities strongly prefer (if not require) MSN's. Think of this way ... they want the faculty to have at least one more degree than the students will get when they graduate.
Keep in mind that without at least a Master's Degree, you will be at the bottom of the totem pole in the world of higher education -- in a position probably called "instructor" or "lecturer" etc. Within the university hierarchy and pay structure, these are the lowest positions. In other fields (such as chemistry, psychology, English, etc.), many of these positions are filled by graduate students in their early/mid 20's -- not by professionals with years of experience. The salary structures are often geared toward those other departments, in which the instructorship is considered part of the educational process for a PhD student on the way towards a full professorship. The pay is often surprisingly low and not competitive with what an experienced nurse can earn in hospital nursing.
I know people who teach as adjuncts because they really like teaching, like the hours, and don't need the money. But you might be in for a disappointment if you are thinking it would be like a "promotion" with a raise involved.