Ah, well I can answer that part. It was because she was the reason the project was being made, she had a contract with FOX. So they were going to want her as the lead, and she'd want it herself I'd imagine. I agree with you about Who Are You.

Yes, the network was interested in a Faith and Spike spinoff hence the scene of the two in the basement that was supposed to be a sort of test scene for how they'd work together. But Dushku was offered money and a contract at FOX and then the WB wanted Marsters to come to Angel as part of the agreement for a S5.