Re: RN - BSN, ADN????
Having an ADN but not a BSN will dramatically limit your choices for traditional MSN programs. Most require a BSN from an accredited nursing program. (Obviously, that would not be a factor with "direct-entry" MSN programs.)
Teaching opportunities will be severely limited without
at least an MSN (not to say you wouldn't be able to get a teaching job, but you wouldn't be qualified, plain and simple, end of story, for
most nursing teaching positions). An MA/MS in another subject wouldn't count in most schools (
legitimate schools) -- accreditation requirements for colleges and universities require that you must have your graduate degrees (or, at least, a minimum specified number of graduate hours)
in the subject you're teaching (that's for all subjects, not specific to nursing).
And, yes, most teaching positions specifiy a minimum of anywhere from two to five years clinical experience. Many also require advanced practice certification in your specialty area.
Fortunately, one of the good things about nursing (IMHO) is that there are usually a few different paths to get to where you want to go!

Best wishes for your journey --
Nursing News