Ok I haven't gone into the shop yet, since as soon as I walked past the place she stepped out and killed someone, so I'm just checking out other things for now. But at least I know where it is now.

In the fire ruins, well I'm kind of on a mission to kill all Immaculates on site (except in that town where I'm supposed to be finding out stuff), so the ones to the NW of the map are dead. Went through the mirror teleporter and killed those. Then met a bunch of Void goats and can't beat them, so I die.

I can't sneak past the other Void monsters. My ranger has a point in Sneak. Not sure what good more points does. Would that make the enemy 'view radius' smaller while I'm sneaking? That would be helpful I suppose.

Lave kills, so I'm not sure what you mean on that last hint.