CapnZapp
Legend
Either you were unclear or I only skimmed your introduction, because you're obviously aiming for the henchmen aspect of the Leadership feat. While I responded to the cohort aspect.Basically, my design goal was to bring back the 3e idea of a character having an "extra companion" or "helper" that has a relatively minor cost (like a feat).
Anyway, what I was trying to do was create companions that weren't useful in combat.
I understand the "action economy" aspects, but feel the Beastmaster attempt at a solution to be very artificial.
To me, if you don't want the extra characters to be useful in combat, simply prevent them from being of a level high enough to be useful in combat.

On the other hand, if a rule allows an extra character to be of a level high enough to actually be useful in combat, you need to give it its own set of actions, or things will feel very strange indeed. (Especially considering we're not talking about a magical summoning spell or mystic bond here. We're talking about a perfectly normal NPC in a game where all other NPCs have their own actions).
So the henchmen aspect of that old feat is probably okay to import wholesale. Sure, I would have liked a rule that integrated better with paragon paths more, but as a quick fix, it's okay. (I don't have my 3E books here, but, wait... *checking SRD* ...yes, the feat never allows a henchman who isn't at least one tier lower than yourself, so it's good to go)
Regarding cohorts on the other hand; in short: 1) don't impose a mechanical cost - this can never be balanced and will take control away from the DM 2) don't impose action restrictions on the cohort - basically because it does not make any sense.
