Welcome to ScubaBoard!
As others have said, you may find going to anything non SLR will be frustrating in the long run, but you may find that being a new diver starting with a reasonable quality compact will let you develop the dive skills you need to really utilize your photography skills.
It really depends on what your goals are for your underwater photography, and I would break those into your immediate goals and future goals. I'd concentrate on the immediate goal - getting in the water and diving as much as possible. You could go the dslr route right away but you'd have to double (at least) your initial budget and the rigs aren't that easy to carry around for a new to intermediate diver - and this will definitely impact the quality of your photos.
A compact would let you get started in determining where you want to go with your photography and allow you to start building a good solid system - start with the strobes. Buy more than you think you are going to need right now - do not skimp on these. Photography is light and underwater light just gets sucked away phenomenally fast!
RAW or not is always a question. Yes, it's a totally fabulous thing to have. Do you absolutely positively need it to begin? Probably not - especially with your very solid foundation of exposure. There are cameras out there that support RAW - Olympus and Fuji are the leaders here - so they would definitely be a place to start. There are also quite a few very good cameras out there without RAW. You won't have quite as much information to work with after shooting, but you can still get strong results without RAW.
Does this help? I hope so...just be aware that it is a slippery slope...once you start, it's just a giant money pit as there is always one more thing to buy
![Smile :) :)](data:image/gif;base64,R0lGODlhAQABAIAAAAAAAP///yH5BAEAAAAALAAAAAABAAEAAAIBRAA7)
But you'd be used to that!
First and foremost, concentrate on your diving - it's the number one thing you need to have before you can get those stunning shots.