That last guy - the gunslinger - comes as the leader model in a Kill Team box. So, him and a handful of assorted GSC troops. So, yes, the core of a Necromunda gang. But I feel the itch to write him up as a Hired Gun for ORB/GorkaMorka, since he suits both settings.
The stats of the genestealer cultists were heavily debated on release more than 1 year ago.
We got several esitions of them since then, all of which have 1 wound for acolytes. My guess is they have 1 wound since aberrants got 2 wounds.