When applying for a NROTC scholarship, can the letters of recommendations/evaluations you receive from your high school teachers for the USNA be used for NROTC as well?
To the best of my knowledge the SA application and the corresponding XROTC applications are independent of one another. You should treat the two processes accordingly, with separate letters of recommendations in accordance with the instructions and procedures.
However there is an exception. DoDMERB does transfer across SA's and is also accessible by ROTC. For example USNA paid for my son's DoDMERB, and Army ROTC was able to use that DoDMERB report to validate his scholarship.
Depends, is there anything specific to the program you are applying for or did the person write a generic character reference? (One would hope they tailor their writing!)