I love the show to death but can't forgive most of the decisions made throughout Season 6 if I'm honest. Giles ditching his deeply depressed surrogate daughter is at the top of that list.
"You're 20 now Buffy. I know you just lost your mum, you just died yourself and were pulled from heaven. I know you are now the parent of a teenager, you have a house you can't aford, you dropped out of college and have no job, and you have a sacred duty to protect the world from evil (for which I am paid and you are not); but I think it's best for me to leave the country so you will stand on your own two feet."
Finding Fred's spiritual remains can be the first case.
Entirely possible. There's a scene between them in 'Dirty Girls' which was written as kind of a mini pilot for the Faith show. (Been a while, might be misremembering. Wanna say I got it from the DVD commentary)