Loot extracted from the DZ by helicopter shows up in your mailbox, accessible from your stash.
My experience with the Dark Zone is that player-encounters are relatively uncommon, and of those 90% are non-hostile players. But also, that’s because I mostly stick to PVE events, which tend to attract PVE-focused players. I have “seen” a hostile player at a loot extraction where he killed another player who was loitering there–I was gone by then but was close enough to hear the gunfire.
It helps that I mostly don’t care about the actual loot; aside from 4-5 DZ-only items, it’s all stuff you can get at comparable quality through regular open-world exploration. There’s some story content though, in the form of collectibles (e.g. comms pickups).