the biggest difference between an RN and NP is that as an NP, you have more autonomy and are able to diagnose and treat patients for a variety of conditions, depending on your scope of practice. For example, if you are sick and go to a clinic to be seen, you can be treated by a NP. As a RN you are still caring for the patient, but you get orders for the medications and treatments from the M.D., PA, DO, NP depending on where you work. If you are sick and go to a clinic, the RN may be the one to talk your vitals and get initial information on what is going on but than you are seen by the health care provider for evaluation and treatment. The role of the RN and NP is various depending on where you work. Many RNs work in the hospital setting on various floors, such as neuro, med/surg, pediatrics etc and provide bedside care- passing meds, monitoring, IVs, etc.
I'm not sure what you constitute as "minor" surgery, but as someone in the FNP program and hoping to work in the outpatient setting, I don't expect to do much "surgically" besides maybe stitches/taking them out, which is the only type of "surgery" I have learned in my program thus far. If you specialize, such as an Orthopedic NP, you can get certified as a first assist in surgeries etc. It all depends on where you want to work and do.
Basically NPs are "advance nurses" because you are in charge of managing and treating acute and chronic conditions. My FNP program is focused on obtaining a thorough history, performing an accurate physical exam, assessing what I think is going on/the diagnosis and the plan in how to care for the patient. If you go the PNP route, you would only be able to care for kids; if you go the family route you can treat across the life span.
As far as teaching, many schools are transitioning to only allowing NPs to teach who either have or are in the middle of obtaining a Doctorate degree. There is speculation that by 2015 it will be required that all NP students will have to get their doctorate degree in order to practice and those who already have their masters at this point may be grandfathered in. It is unknown what will really happen, but something to know if you pursue an advanced degree-that by the time you do, it may very well be required to get the doctorate as well.
I hope this helps!