Regarding the armor, it's very likely that they're be only one set. They way I'm expecting Bethesda to do the aliens on the ship is something near the one's from Mars Attacks, only using armor on Earth, and basically nude on their ships. Probably near the end of the DLC, you'll get the chance to loot the armor, and hopefully, (God, I hope so), weapons from the West coast, and a few alien weapons. Possibly from killing the head alien, becoming friends, or letting him probe you.
Yes.