I notice the HD progression for fighters has been changed. Will this be staying in the new version?
The fighter HD progression was changed between v1 and v2 of the DD Ref Rules because v1 implied that fighters would add 1 HD per level forever. In v2 they progress this way up to 9 HD, and thereafter gain 1 HD per 2 levels (much nearer to the original fighting-man).
The upcoming hardback DD edition will have exactly the same HD progression as the Ref Rules v2. In fact, you can already download the preview of the next edition's text and see it for yourself