[While Frieda's expression turns mildly unamused for a moment, she doesn't seem seriously scared - if whoever lives here wanted to target them, they'd have had ample opportunity already. Besides, she puts stock (perhaps too much stock) in the civility of those inhabiting these marshlands.

As for who would be this other group's leader if they were also on a journey to what comes afterwards:]

Another Ferryman. No one said that there's only one, right? That could only work out if time worked very differently here - which I suppose is the case - and only certain people, a small percentage of all who die, arrived here... which, granted, is likely true as well. But even so, it'd still be a lot of work for only one Ferryman!