[titanss]

#4 & #6 use the same bolts. Is #6 threaded if not it is a newer model reinforcement bar the bumper is Pop Riveted to it.

 

[titanss]

This will help you get started: 620 Front Bumper :: Body Front, Roof & Floor :: Genuine Nissan Parts :: Titan Parts (A60) 2004-2011 :: Nissan Parts, NISMO and Nissan Accessories - Courtesyparts.com

The service manual does not have a part number for the bolts, they have a 10mm head and are fine threads, the dealer may be your best bet on getting the correct bolts.

 

[titanss]

Could you also tell me what holds #7 together if you could see them on your XE? These holes are smaller than all the holes in #6 and I am curious if there are any gaps between the bumper and the fender so they don't rub together?

These 2 points have plastic inserts that go in to the holes in the skid plate and fender. The center tabs on the bumper go beneath the skid plate after it is installed and 10mm heads screws (not bolts) go there. If i remember right the fender use 8mm headed screws to hold the bumper tight against the fender, so there is No gap between the fender and bumper.