Current NROTC instructor and former helo bubba here.
First off, talk with your aviation advisor about your plans.
Second, how do you feel about the Marines? Right now Marine option mids can guarantee a flight school spot if they get minimum ASTB scores and qualify medically.
Third, I second the don't sweat the stats comment. The board considers four things: your grades, your ASTB scores, your PRT score, and your aptitude score (basically your ranking and a reflection of good of a guy/gal you are). Nearly all of those are within your control and all you can do is your best. Study hard, work out hard, be a positive force in your unit, and see how the cards fall out.
Fourth, you don't have to list SWO but you do have to list one nuke preference (submarines or SWO-N).
Regarding USNA vs. NROTC - I seem to remember seeing some recent numbers and it's about even. But again, you can't do anything about that.
Let me know if you have any more questions.