If by FF you mean Field Force, do not address them by first name. Use appropriate rank or title, unless requested to do so otherwise:Do I just use their first name? Or should I use Mr? I'm unsure because they are not technically a teacher or anything, but they still do a lot in the admissions process? What did you guys do?
Just thought I'd add in the south (or at least NC) it's Mr. Steve or Miss Betty (regardless of marital status), if you know them. Otherwise it's the usual formal Mr./Mrs./Miss.On your portal, in the field force tab it will state what the appropriate title is (Mr., Mrs., etc.). Always address them formally, respectfully, cordially, and professionally; they are not your buddy. Create a good first impression because you only get one, and they will be interviewing you in your application process.