RE: When to use the wave fin?
The 07 models only come with one fin. It was decided that despite that the two fins delivered with the 06 boards both were very good, none of them were an ideal fit for the type of sailing most people did with the boards. The wave fin was great in waves and OK for some freeride stuff and the other fin great for pure blasting but a bit big and stiff for more recreational blasting (including jibes and stuff). So, a new fin was developed as a "perfect match" for the Kombat.
If you want to tune the board for pure waves or pure blasting, you can still look for a different fin as an after market item, but I believe most sailors are more happy with the crossover fin and if anything will rather complement with a different size of that type of fin, especially I think very few people prefer the board with the freeride flow fin compared to the Drake Crossover.
So, there is nothing wrong with you boards accessories.
PS. Early version on the 07 Kombats did come with the two fins from 96 since the 07 fin was not yet ready. DS