Hannelore is too kind-hearted for this grim world of ours.
Chiming in on David Whitaker possible being an alcoholic: I agree that there's no hard evidence and it's purely speculation, but I think it's a theory with a lot of merit. If it was ever revealed to be the case, then I think it's been foreshadowed very well, even if that wasn't the original intention (and of course, Faye herself
insisted that he wasn't an alcoholic). It should be noted that Faye's mother did mention that
he didn't have anything unusual in his system, though a negligible blood-alcohol level may not be classed as unusual, compared to hard drugs or the like. It's possible that given her strong anti-alcohol stance, Faye's mother simply glossed over that detail in that chat, or it could reasonably be retconned as such. It's one line of dialogue in what is now fairly early on in the strip, so it wouldn't be a particularly awkward retcon, especially since the rest of the backstory would fit together quite well...again, if Jeph decides to make that canon.
As for Arthur, I'm guessing he'll mostly just appear whenever Faye is at the meetings, along with the other members that we briefly met. I don't think the strip needs another principal cast member, and I think it's better for Faye - in-universe and from a narrative perspective - if that particular part of her arc is separate from her more familiar social circle, with the possible exception of Hanners.