It would seem to me that in order for a ship to run smoothly and with happy, non heretical crews you would need a certain ammount of Navigators, tech Priests, echlisiarchal priests and Astropaths. I usually give each player control of the contingent that's within their area of expertise. On average the Explorators in my game can expect to lead about half a dozen Tech Priests from DH, while the missionary can count on a similar number of followers. But the Navigator and Astropath each got two other members of their order to act as relief drivers and whatnot as we as two attendants such as acolytes or body guards.
I figure the Trader gets a ship, Warrent and everybody on the ship. And the Senchal gets to be the power behind the trader so it's not at all unfair to give the other players some underlings in my estimation.
I was wondering what everyone else does and what sort of numbers of specialized staff you guys have on board a starting RT ship.