You have indeed opened a can of worms. With the Fuji S2, you have a few choices:
Ikelite
Aquatica
Sea and Sea
Subal
Seacam
I recently purchased an Aquatica housing, TLC strobe arms, and Inon Strobes. I went with Aquatica because it seemed to be a good balance between the botique, but very cool, Seacam and Subal housings, and the three other manufactors of the more economically priced choices. They are all good housings, and as I once heard, it is the indian, not the arrow.
One note, the Aquatica is a bullet proof aluminum housing, while the Sea and Sea and Ikelite are of the acrylic box genre. Also, Aquatica supplies an 8" dome port which is perhaps a little more desireable than the smaller dome port from others. Whatever choice you make, you will enjoy the end result with your rig.
When you are choosing your strobes, I strongly recommend the Inon strobes. They seem to be a fantastic package to include small and compact in their list of strengths. When traveling with this gear, small and compact becomes very important.
Good luck and start early on assemblying your rig. The industry is plagued by vendor supply issues and it will probably take a little longer than you originally planned to complete the assembly of your rig. Mauricio Handler(Aquatica only), Ryan Canon at Underwater Photo Pro, or Jason at Backscatter are all very helpful reps of the different housings available for the Fuji S2.
As far as camera selection, search the DSLR boards. The D100/S2 debate has generated many megabytes of messages on wetpixel for you to review. They are both excellent cameras. Search the boards, you will be overwhelmed with great info.
Regards,
Mike