In the Rules description of Infantry Command, "Each level of this skill allows the player to command an additional personal squad of NPCs/droids/creatures." Is this personal squad of NPCs/droids/creatures just a party of yours?
In Ship information, does Max Passengers mean how many Party Slots can be brought into the ship?
Every player can command one party and at least one squad for a total of 24 NPCs.
Infantry command skill increases the amount of squads a player can command.
Max passengers value includes yourself, so a ship with max passengers value of 2 can carry you and one other passenger, be it droid or NPC. And while droids can have a lower party slot value meaning that you can have more of certain droids in your party than 12, I believe they still count as one passenger slot, unless they are repackaged (=deactivated and put in a box).