I'm a nurse in Florida. ARNP stands for Advanced Registered Nurse Practitioner. I'm on my way to becoming one and I just finished 135 clinical hours with an ARNP for my BSN (I LOVED it)!
Here's the track I recommend (the only reason I recommend doing an ADN program is because it's much more hands on and stronger clinically based than doing BSN first but to each his own):
2 years in an ADN program.
1 year in a full time RN to BSN program (I recommend getting at least a year experience before doing so because it really means nothing if you don't know what the heck you are talking about. However, in certain parts of FL hospitals are on a hiring freeze soooo if you can't get a job, going straight into an RN to BSN program [unless you start in a BSN program] will help you get hired). I graduate next week from this, it was super intense because I'm working full time as well, but the program itself was a piece of cake, just time consuming.
Then onto a masters program for your practitioner. I personally recommend University of Southern Alabama online MSN practitioner program unless you really want to be in class for it. Full time is 4 straight semesters, part time is 7 straight semesters and they help you set up clinical with your preceptor. Hopefully in your BSN program, you'll get to precept with a practitioner so you can kind of get an idea of where you want to go. I'm going to do the adult primary care practitioner program but there's so many out there! Keep in mind if you want to be a CRNA (certified registered nurse anesthetist), you need ICU experience and it's a classroom setting!
Also I'd like to mention, after re-reading your post, is that if you already have a bachelor's, some universities offer an accelerated BSN program for students that already have a bachelor's degree in another field so that may be an option. It is a quicker way than the ADN (associate degree in nursing) but it's not as strong clinically (just my opinion, I've been working in hospitals for many years).
Hope this helps