A: Surprisingly, yes. The Genius Loci mechanic is random enough that you can play the "Claim Jumper" scenario solo. Run both gangs yourself, but let the Genius Loci table make unpredictable decisions for you.
Here's some text based on what "Necromunda: Halls of the Ancients" could entail: necromunda+halls+of+the+ancientspdf
The lore explains the deep-seated hatred between the Squats and Ash Wastes Nomads A: Surprisingly, yes