Phat,
The coudiness has no advers affect on the fish. Have you ever been to the beach after a storm? It is much worse, and the fish survive fine.
As for seeding the sand, I recently upgraded to a 180G with a new sand bed. After 1 month it was teeming with life. The liverock is enough to kick it off. If you want to add a kit I am sure it couldn't hurt and might add some diversity to the tank but in my opinion it is not worth the dough.
I will reiterate that I don't believe that the cloudiness has any adverse effect on the fish. As for using Carribsea, the only thing that I will say is that the particle size is critical, and anything that doesn't make the water cloudy probably has particles that are too big to be most effective as a DSB.
Also, you will have mini-sand storms for the first couple weeks anywhere the sand gets disturbed. After a couple weeks, the bacteria will coat the sand and you will not have that problem. I was told that same thing before I started but didn't believe it because any minor disturbance clouded the water for a couple hours. I believe it now, though because I can really dig in the sand and the disturbance settles in less than 2 minutes.
GL, and don't worry about the fish and corals. I did burry a cleaner shrimp that I couldn't catch.
E