40k Rules question

Greetings, and a question for someone smarter than me:

The way I've learned to play under Randy's tutelage (and it makes sense): Lets presume I'm playing Orks, Ghazgul is in my army, and that I have a trukk full of Ork boyz with a Nob in them.

On turn 2+, Ghazgul can declare a Waaagh, which gives the entire army the fleet of foot option; which basically gives them the ability to run D6 (with Ghazgul, a full 6") during the shooting phase and then assault. The way this would look:

Trukk full of boyz (red paint on the trukk) moves a maximum of 13". Boyz disembark 2". Fleet forward 6". Assault 6". This is my understanding of how things work. I was googling around trying to find the FAQ explaining the 2" disembark, and how the back of the base must touch the 2" marker, not the entire base be within it completely, and I ran across
this FAQ. (click that link)

On page 3, I see this:

Q. Can a unit with the Fleet special rule assault after disembarking from a transport?
A. No, it cannot. The Fleet rule simply removes the prohibition of assaulting after running.

So now I'm confused. If my trukk moves its normal distance (whatever that's called), stops, and the boyz inside disembark, that's a movement. They still get to shoot and assault. If I've happened to Waaaugh, why would my one-turn fleet prevent me from assaulting?


*EDIT* I was reading the DakkaDakka forums, and I think I found the answer, although I don't have a rulebook handy to verify...the folks there said that the exception to the "assaulting after disembarking" is for open-topped vehicles, such as my trukks.

Does that mean that if I add a hard cover, I can no longer assault out of my trukk?

*further edit* Further reading brings up another question - the FAQ also notes that a transport (trukk) can shoot at different units than its passengers, since the vehicle is to be treated as a different unit for that purpose; and I ran into more discussion...a unit can't embark and disembark same turn...and the embarking counts as that unit's moving phase.

Can a unit move up to a trukk, embark, and then the trukk take off across the table? From the things I've been reading, I presume the answer is yes?

They can Assault after Disembarking and fleeting out of an open topped vehicle or Landraider.