Not forums but if you are serious about the business side of commercial writing in the ebook age you should check out:
http://kriswrites.com/category/business/
Ms Rusch has a series of very educational weekly columns there.
Case in point, this week's column on the difference between working to be a published author and building a writing career:
http://kriswrites.com/2013/08/28/the...s-publication/