The actor who played Bill (Jim Storm) was involved in one of the most famous recasts in soap history on One Life to Live. When JS decided to leave the role of Dr. Larry Wolek, the show had Larry involved in a fire. When Larry's bandages came off, he was being played by Michael Storm, Jim's brother. Jim Storm also played Neil Fenmore, Lauren's father, on Y&R for a while though I don't recall his being a major role.
I think it was a smart move to hold off on introducing Stephanie immediately. In a premiere, you are bombarded with all new characters and settings, and all that exposition will make a new viewer lose track. Giving Stephanie a less hectic introduction allowed the viewer to "absorb" her character better, much like being "fashionably late" to a party in order to make a grander, more memorable entrance.