Dr.Bill, expert on all things watery and on or near Catalina (as he's a marine biologist who has been living and diving there for the last 38 years), has only seen ONE Great White there and it was hightailing it out the way.
Don't worry about sharks there. As it is it, the "attack" the media are talking about was NOT an attack. A shark (if it was a shark, let alone a great white) bumped someone off of a kayak. No biting = no attack. Besides, a kayak on the surface looks a whole lot more like shark food (seals and sea lions) than a bubble blowing diving at depth. Review the records, minuscule number of shark attacks on divers ANYWHERE IN THE WORLD as compared with the small number of attacks on surfers, snorkelers and swimmers.
As for the Casino Dive Park deaths, from what I've been able to garner from the reports, they are mainly caused by poor medical conditions of the divers. There are no reported deaths, that I'm aware of, from marine life or other inherent dangers of the dive site.
That said, if you've not dove in the ocean, especially around kelp, hire a DM/Instructor/Guide to lead the dive. You'll relax, have more fun and learn more. There are two dive ops on the island, Scuba Luv and Catalina Divers Supply. Both teach and lead dives at the Park so often, that each has its own "other instructors keep the heck off of" instructors' rings there.
Have fun and get a dive in!