Ross,  thanks for the 411 on the straps. Put them on last night.

Now my question is, in the bottom of the main compartment, there are three cords sewn to the bottom of the pack. They are about 6" long and doubled up. Is there a reason for these? There are also three "D" rings sewn to the hem of the secondary compartment. Do the two relate to each other? If so, how?

Does any of this make sense to any of you?

Yup, it makes sense.  They are there so you can shorten the pack if you have to carry smaller loads.  That way if you're just carrying something smaller, it doesn't flop all round in like it's in a big bag.  You just tie up the cords to the D rings to whatever length is required.

The smaller pocket inside the main compartment is for a manpack radio (though obviously you can use it for other things).

The pockets on the outside are "tunnelled" so you can attatch a Machete, wood handle E-tool, etc to the webbing that runs around the top outside, and run the handle/etc through the "tunnel" between the pocket and the main compartment.