Once you enter the outpost, if you head south, near an overturned vehicle is a warhead, which you can detonate for the Warhead Hunter achievement/trophy/challenge. Once detonating the warhead you can gain access to a truck with many military supply crates in the back. The other trucks also have various loot and containers in them as well.
Warehouse stash key - located behind the truck with the warhead in front of it. Unlocks a gate to the northeast.
Ulysses log Y-17.21 - located behind the locked gate on the northeast side of the area, on a metal shelf immediately to the left.
There is a Ralphie poster for the Feel Like A Kid Again challenge behind a locked gate on the northeast side of the area.