When dealing with the Leadership feat, here are a few of my thoughts on the matter.
1. I usually do not grant followers unless the PC has some kind of task for them to accomplish, or place for them to be. In your case, your PC wants them to serve as retainers, so I'd allow it. But for a PC with no base of operations, I find that a dozen tag-alongs are more trouble, for both player and DM, than they're worth. So no followers. Though if later a PC were to come into circumstances where followers were useful/complimentary, he could certainly claim the proper number of followers at that time.
2. When defining the Follower-PC relationship, I think of a Rock Star and his groupies. They are basically in awe of him and will do nearly anything he says. When defining the Cohort-PC relationship, I think of Batman and Robin. Batman is clearly the senior member of the partnership. He's the hero, the focus. He's the one responsible if the [ahem] hits the fan. However, though Robin follows his lead, that doesn't mean that Robin won't have a different opinion, or even argue with Batman if their opinions come into conflict. Although Robin is Batman's sidekick, there is a certain degree of independence there.
3. If there are many players, I'll have the player RP the cohort, and control him in combat. If there are fewer players, I will RP the cohort (to create some of that independence noted before), but still have the player control the cohort during combat.
4. I never make the cohort important to the main story, except in relation to the main PC. The cohort is there to be an aid to the PC, not steal spotlight time from the other players.