My two cents, for what it’s worth considering the fall of the value of the $US 
. (Remember, my opinion is no more or less valid than another is, and should not be mistaken as an official answer unless the FAQ Team makes it so)
Pg. 40
VEHICLES AND USING ACTIONS In general, when a Vehicle is activated, any crew riding within it must expend their actions simultaneously. If the driver uses his first action to drive, any other crewman must spend their first action before the driver can spend his second. If the driver spends his second action before the crew takes their first, the unspent first crew actions are lost, unless a Special Ability declares otherwise.
Models inside a transport are considered a part of a single passenger Unit. This passenger Unit takes actions just like an additional crewmember. During the passenger Unit activation, one or more of the transporting
1 models may elect to disembark by spending one action. They must then spend all their remaining actions before any other member of the crew or passengers may take an additional non-Wait action. Note that any number of passengers may elect to disembark during passenger Unit activation. See Armored Personnel Carriers for more detail.
The above rule is, in and of itself, clear. Models riding inside the transport are treated like crew, but are a separate Unit who must spend their actions in conjunction with the crew of the vehicle while riding in the vehicle. They may disembark the vehicle during any activation, but then must spend the rest of their actions before the vehicle returns to its activation, no matter how many models disembark. They have as many actions left as their original number of actions less the number of actions that the Vehicle has taken, plus their current action.
Pp. 90-91
Armored Personnel Carriers (APC) Vehicles designed to carry troops are noted as APCs in the Special Rules portion of their Profile. The number that follows this designation represents the number of SZ 2 models that it can carry. A Vehicle may carry double the amount of SZ 1 than it can SZ 2. Alternately, a vehicle can carry half that amount in SZ3 models.
22.0- Boarding a Transport (Embarking) A model that wishes to Board a Transport must Move into Base Contact with the Transport Vehicle and expend one action to Board. Once boarded, the model’s Turn is ended and it is considered to be a part of the Vehicle’s Compliment until it disembarks.
Models may board in any order, and may start the game deployed inside of a Transport. Should all the models in a Squad not make it into the transport or are too many for the capacity of the Vehicle, and then those models are considered left behind. Unless the Squad leader is with them they will be considered out of Command Distance and suffer the penalties associated with that state.
For an embarked modes
3, place the Unit Card of the Boarded model next to the Transport Vehicle until that model Disembarks.
The sophisticated locking systems and vigilance by the Vehicle’s crew keeps enemy models from boarding a Transport. Therefore, no enemy model may Board a Transport Vehicle.
2.1- Traveling in a Transport Unless otherwise stated in the profile, models inside a transport are considered protected by the Vehicle. They cannot be directly harmed unless the Vehicle is destroyed. While in the transport, Squads being transported are considered a single passenger Unit. During this passenger Unit activation, one or more of the models may elect to disembark.
2.2- Disembarking a Transport During the passenger Unit activation, one or more of the transported models may disembark. Models that disembark spend 1 action to leave the transport. They should be placed in base contact with the transport exit point, and are required to spend their remaining actions before anyone in the transport may take another non-Wait action. Any model (friendly or enemy) in base contact with the transport’s exit point will block transporting models from being able to disembark.
Again, the rules are clear, and I do not see any confusion. Models riding as passengers are not, actually, crew, but must spend their actions in the same order as the crew until they disembark, at which point they must spend all of their actions before the vehicle resumes spending its remaining actions. In other words, if they wish to disembark on the first action, then the get to disembark with one action and spend their remaining actions before the vehicle spends it second action. If they do not disembark on the first Vehicle action, then the passenger Unit loses its first action. If they wait until the Vehicle has taken three actions, they will only have their original number of actions, less the three actions the Vehicle has taken, plus their current action.
Example: A transport is carrying a Squad of Imperial Regulars (four troopers, a Sergeant and an HMG Spec). The player activates his Transport, and Moves on the first action. The player then decides to disembark the passenger Unit during the passenger Unit activation. The Player moves the first model into base contact with the exit point of the Transport on its first action, moves 4” on its second action, and fires at a Machinator Mk I on its third. The next model is moved in similar fashion, and all models are disembarked. The Vehicle then spends its second action to Move. Remaining actions are spent.
Example: A transport is carrying a Squad of Children of Ilian (16 kids and a Scion). The vehicle spends three actions Moving. The player then wishes to disembark the passenger unit. The first model is moved into base contact with the exit point with its third action, and winds up blocking the door for any other models wishing to disembark. The activation for the vehicle and its passenger unit is complete, and the lone disembarked child is out of Command Distance.
Unless I am misunderstanding something, disembarking from a Transport is clear. Where there may be some confusion is whether a Squad that embarks a vehicle can then disembark during the Vehicle’s activation. The answer to this is not as clear.
Once a model embarks a vehicle, its turn is over. Therefore, the model cannot disembark until the [edit] following turn.[edit] However, because the model(s) becomes part of the vehicle’s compliment, does this mean that the vehicle’s turn is over, now, too? I would say, “no.” After all, a vehicle could move, then receive troops, and can disgorge troops during its activation, therefore it should be allowed to receive models, then move, or any combination of moving and receiving/disgorging.
Have I cleared this up, at all? Have I made it less clear? Does this make sense?
I welcome feedback and counterpoint.1 - should read, "transported"
2 - this has been FAQ'd
3 - I believe that this should be translated as, "For any embarked model(s)"
