After you let the Ghouls take off for the "New World", where do they go? It can't be too terribly far since some return to help Novac during/after the final battle.

When talking to Johnson Nash in Primm (Mojave Courier rep), he mentions that another person refused to do the delivery, telling Johnson to give it to "Courier #6", in other words you.
Do we ever find out who this other guy was and why he wanted you take this delivery?
Also, right outside the Courier office in Primm is the guy who delivered #4. Are the other 4 delivery people to be found someplace?

In Camp Forlorn Hope and vicinity, I found several letters. The highest number I found was 9, but I didn't find all 9 letters (assuming there are 9 ). Is there any point to these letters, or just to give you a feeling of how depressed/desperate/resigned these people are?

In the north is a northern passage that you can't get too unless you 'tcl', and then it only leads to a passage that heads north. The other end is an exit to the Mojave that doesn't work.
Also, in the Tops, through the door by Yes Man is a hall to a locked elevator. When 'unlock'ing the door, I do go to a long hallway that leads to a door that opens into nothingness....
Can I assume that both of these are set up for future DLCs or just a irritant

Feel free to add your own unknowns here and let's see if we can together figure out what was suppose to happen