As far as Gotham Knights being forced to end in order to make Batman Beyond...I don't think so. Kids WB definitely wanted a series that was focused on a young Batman, but I think it was the decision of the production team to end the latter show before starting work on the former.
Yeah, I'm guessing as much. I also recently read something akin to them running out of stories for the Gotham Knights / BTAS. So moving on to Batman Beyond allowed them to do something new as there wasn't anything left to do with BTAS.