Stowaways should get a PDA.

[Zamujasa]

don't you get a free emergency o2 + breathmask in your bp box by default?

As Urs said, it's random. I wrote up some details on how spawns work, though it's for 2016.

They could get one of those big unwieldy air tanks like the scientists do, much less useful than an emergency tank. Or like 3 units of salb in them.

I like the idea of the emergency o2 tank better because the huge tanks would stand out a lot for someone who was trying to stay hidden. Salbutamol also wouldn't help since that doesn't stop you from suffocating, it just makes you die a little slower.