Until you have an official job offer from HR in hand, you don't have a job. So it doesn't matter what the nursing manager is telling you right now: she may end up changing her mind, or a better candidate may come along, or she may lose the postion due to the budget, or whatever other reason that may result you in not getting the job. It would be wise to broaden your job search to include other facilities as well as this one.
As far as the dymanics changing if you go from CNA to RN...well, that's a hard one as I don't work in your workplace and I don't know what the unit culture is. Based on my experiences in different workplaces, we had techs/CNAs graduate and return to work as RNs on the unit, and it didn't make any difference. No one considered them as still being unlicensed, and they certainly weren't treated as such. But then again, I work in psych, where everything is a little different
You are the best judge of your workplace...what are the vibes that you get from it? What's your gut feeling telling you? Is it saying, "Yes, go for it!" or "Chewie, I have a bad feeling about this..." More often than not, the gut feeling is usually on the mark.
Best of luck in your job search.