Captains and SFO's get 'F' priority if not travelling with dependents under 12 years. 1 in the first 4 years (after 6 months) and 2 after that.
Onload priority on 'bookable' concessions is quite high, standard ID90's are even onload priority with all other departments with date of joining deciding who gets on first. Bookable does not mean you are guaranteed a seat/flight, you can always be bumped for commercial passengers.
Personally I use ST quite a bit and have found the staff and my colleagues on the aircraft to be most helpful.