This is what you need to fill out on the form, or at least what I picked up while reading through it. Take with a grain of salt, since I might have also not understood the form, so any corrections from someone like HCopter of Flieger would be greatly appreciated!
Rank - Cadet
Current amount of SGLI - This should be $0, assuming you are a direct admit to the academy and didn't enlist prior to applying for USAFA. $400,000 is automatically set as your policy amount, unless you tell them you want otherwise.
Unit Personnel Clerk - DON'T TOUCH, this is in a marked box that says "For Branch of Service Use Only". I just left this blank, since you can always pen an answer into a form but can never pen an answer out of a form. Better safe then sorry.
Hope this helped!