It probably depends on who the publisher is. I would imagine smaller publishers would probably give better deals as a way to entice talent, whereas larger publishers like Random House would probably have a much bigger paper-publishing business to support and couldn't afford more generous terms.
Any time you're using your new business to "support" the old business, you're doing it wrong. It should be the other way around - your old cash cow business should be used to support the new business that will take you forward.
