On the surface we have Faith as the ultimate loner, who's cut off the other slayers and their sisterhood. She's losing herself, losing the battle, losing the meaning of life. But if we look at the situation more closely, it's Buffy who's losing it.
Yes, that's how it comes across. Faith is more morally right here than our traditional good guys, and she, for the first time in her story, has a chance to make a stand *against* the "good guys" and show them the way, rather than follow good guys because she doesn't trust her own judgement.

Also I agree - the more they torture them, the more we love them. And it's very obvious whom BKV loves here. Seriously, it's the most compelling Faith I've seen so far, except maybe on Angel-4.

Gigi being raped - no, don't think so. That one would leave a mark. And with her upbringing she would be disgusted to no end with one of the "commoners" even touching her. I rather imagine teachers getting fired one after another after Gigi's enraged fits to her parents. And maybe a lot of that was in her imagination, too.

Roden: we know too little of him and his goals to draw any conclusions yet. And his powers could be limited to only summoning Buffy to the place where Gigi is, or, as was mentioned, maybe the magic he aimes for only works when a slayer kills the slayer who's the source of all other slayers powers. Or some such. With Joss & Co is better not to dig for technical details - he concentrates on characters impact from his world than on the world itself.