Is there a specific type of memorandum guideline to follow if you're writing a short biography to new cadre to introduce yourself?

Hey, don't know if it's different for ADA, but at IBOLC, we never did anything of the such. They gave us a specific assignment where we put some information about ourselves on a note card, but making a memo beforehand is not necessary. I would just wait till you report and do whatever assignment they have for you to get to know you.

This isn't necessary. They will be meeting a lot of new 2LT's and your letter will most likely be white noise. If you do decide to send something, keep it short. No need to tell them your life story. They won't read it all anyway. I'd keep it to something like "Hello, I'm so-and-so, I look forward to training." But again, it's certainly not necessary.