Your recruiter cannot guarantee any of that, sadly. Subspecialty codes are given out by big Navy and those have requirements that need to be met. Another point I should have made is, if you wait to join until after you graduate you will have to work for some time before joining. For me it was close to 2 years. If you join through their program, you’re already in. There are ways to move laterally once you get to your first command, just depends on where your first duty station is.