I could opt for this, but if I were to join ROTC without the scholarship and receive it the next year, would I have to pay the first year's tuition?
Also, is it possible to receive an ROTC scholarhsip whilst at a service academy?
Yes, you would have to pay the first years tuition if you are not awarded a scholarship for that year. However if you get into an academy, the tuition to you, is free. With relation to tuition, the purpose for an ROTC scholarship is to pay for your college and the academies are already paid for.
If you accept an appointment to an academy, you are saying you are willing and committed to serving that branch for the required five years. Thus, if you don't like the branch but you get accepted to the academy, don't accept unless you want to serve in that branch.
You would be responsible for tuition for each semester you enrolled prior to receiving a scholarship. It could end up being all four years of college. Many folks I know end up in that boat.
I do not know if you could technically be allowed to win a ROTC scholarship. Even if you can, you would certainly need an excellent answer to the question of why ROTC after receiving an academy appointment. Better be a damn good one because I think such a move, even if allowed, would be highly suspect. But that's just my opinion. Your mileage may vary. Hopefully someone in the know will chime in with a definite answer on this portion of your questions. It certainly begs the question of how you schedule your PMS interview, secretly send your college transcript, etc... so you might as well ask admissions now to get a definitive answer.
Aside from that, I have to agree with the YellowRoseofTexas.
You can apply for and receive an NROTC scholarship while at a service academy. Anyone can apply as long as they meet the minimum eligibility requirements. I understand that finances may be a concern, but I'd still recommend going to the desired NROTC university freshman year.