Actually CB is a five minute bus ride from Citywalk. This is not like Disney where everything is so spread out and you would Not be that far from RPR. In fact the walkway goes right to RPR and then cuts over.
As for the express pass, Unless you're traveling at busy time you really don't need it. Plus you do get early entry to Harry Potter and you can't use express pass on Forbidden Journey or Gringotts anyway.
I hope I really don't offend anyone with this post. I just think it is a lovely resort and wish people would give it a chance even if it does not have express pass. But I can see the point if they are there during the summer or holidays. I used to be a hardcore Disney hotel person and CB as well as RPR have really just turned me around.