Hi, as Dado said it is possible to see all that stuff in 9 days, but I would be exausted and have a complete mess in my head.. My recommendation would be to skip Rovinj and Krk because klima is simillar with Zagreb and inner land, also they are bit at north.
My choice and order would be: Zagreb 2 days, Plitvice 1 day, Zadar 2 days, Split 2 days, Dubrovnik 2 days. Instead of Zadar or Split (both on the coast), you can squeeze one island on the mid Adriatic - Hvar or Brac.
Driving:
depends on your mood and budget I would recommend highway innland (Zagreb-Plitvice-Zadar) it cost arround 23us$. It is very fast an comfortable. After that you can go, as Mashka said, by normal seaside road next to the sea, you will pass lots of little cities, jump into the water and enjoy.