Just booking the Haven does not give you Specialty Restaurants, but the Free at Sea will. Probably two for a week long cruise,
While the menu in the Haven restaurant does not change (they do sometimes have specials on longer cruises), the menu is very flexible and the staff will likely be able to get you pretty much what you want any time, but may need some notice. As far as breakfast goes, the Haven restaurant has a buffet every morning with fruit, yogurt, pastries, etc. in addition to the menu. There is also a continental display in the Haven observation lounge. There is muesli. I’ve never tried it, but have heard that it’s really good.
You will not be disappointed.