Greg responds...

1. Yes.
2. Brendan & Margot were in "Awakening". They had lines. They were in the script. The animation is done last. In other episodes we began using them as background characters. That became amusing to us. So we kept using them as recurring. We made a particular effort to parallel their appearance in "Hunter's Moon" to their original appearance in "Awakening". Later, I decided to make more use of Brendan & Margot in the third season -- develop them beyond their cliches, which is why Margot had such a prominent role in "The Journey". But then I didn't do the rest of the third season, so I had no control over how Margot was used or how Brendan wasn't. But the animators only put in the characters we told them to use. As far as I know.
A LITTLE BACKGROUND (aka GREG'S ABOUT TO RAMBLE):
"Once upon a time their were three brothers..." PART ONE
The year is 954. The King of Scotland, Maol Chalvim I, is 66 years old. He is very ill.
He has two sons. They are half-brothers. (Maol is the father of both, but they had two different mothers, both of whom died in childbirth.) The eldest son, Duff, is 42 years old. The youngest, Kenneth, is 22 years old. Despite the twenty year age difference, they are the best of friends.
Maol Chalvim also has a new, young wife. Very young. And very pregnant.
She is 18 years old, and her name is Katharine.
On his deathbed, Maol begs his sons to support each other and to protect his third wife and their child. The brothers vow to do just that. Duff assumes he will be the new king. Kenneth assumes he will be Duff's strong right arm.
Indulf has other ideas. Indulf is a 50 year old nobleman and is, himself, a descendant of kings. He has a 32 year old son named Culen, and hopes to launch a dynasty of his own. While Duff and Kenneth wait by their ailing father's bedside, Indulf makes alliances. While Duff and Kenneth close their father's eyes for the last time, Indulf gathers his troops. While Duff and Kenneth take their father to be buried on the holy Island of Iona, Indulf has himself crowned King on the Lia Fail at Scone.
Needless to say, Duff and Kenneth aren't too pleased. They prepare for battle, but Indulf pulls his trump card. He has Katharine. And he will kill her if they raise a sword against him. Bound by their vow and their sense of honor, Duff and Kenneth retire to a family stronghold and wait.
At Edinburgh, Katharine gives birth to a boy. She names him Malcolm, (which is a more modern variant on the name Maol Chalvim). Indulf is now willing to return Katharine to her step-sons. But the babe will stay in his custody as insurance. For obvious reasons, Katharine chooses not to leave.
TO BE CONTINUED...