FAQ

As explained in the movie, he mailed the mask and gauntlet to a P.O. Box. However, a mailman shows up at his house explaining that his payments for the P.O. Box were overdue and so the items were re-directed to his home address.

This can likely be attributed to the numerous re-shoots the film went through. Shane Black explained that the original third act took place during the day and it just didn't look right. So it was switched to night time. As we see when Traeger enters the ship, it's at night. Once inside the ship he is wearing sunglasses which he immediately takes off. It's likely this was from the original ending and he entered the ship during the day and had his shades on. Thus creating a continuity error.

Likely an answer was filmed but got lost in the edit/reshoots. The most likely explanation is that when the Loonies are holed up at the motel, we see dozens of bikers are also frequenting the motel. The motor home can be seen parked there.

It's possible the bikers were gun runners and they stole their shipment. Alternatively, one of the group was in contact with a black market arms dealer and met with them to purchase the weapons.

Again, likely another plot point lost to re-writes and re-shoots. There was even an action figure released called the "Emissary Predator". It wore American army fatigues and carried an M249 machine gun. Beyond that, nothing more is known.

Director and Co-Writer Shane Black has confirmed that the film will be an "inventive sequel" to the movie Predator (1987) (1987) and not a remake. To quote Black, "Why start over, when you've all this rich mythology yet to mine? [I Like] the idea of expanding and exploring the existing Predator mythology, rather than hitting the restart button." (Source) Essentially, the Predator franchise is an anthology series. Different characters in different locations instead of a continuous story focusing on the same people.