Scheisser

Yes, you have to do some quests first. I think it was around mid or late Act 2 when he got usable as a member. I am not sure which quest, likely the questline regarding the sick man in the Last Light Inn / little boy and his ghost.

I got a quest log message that Halsin had left, though he was still in the camp and was usable in the party. Everything worked as if nothing happened.

Could be a bug.

Guess it depends on the device, for me it is good if there are enough space on the edges so that the air can flow easily below. So the slices have to be small. Then the end result is more even, cheese remolten and the bottom does not get too soft or soggy.

Airfryer is also great. Similar to this.

Sounds like an easy way to lose the keys and forget the thing. Have to always have the keys in the pants or risk forgetting them… at least until the front door gets closed.