There is little chance of you being able to get one unless you already have a source for them. As far as care it would be similar to S. bandensis they reach similar size and come from roughly the same area. However, it is not an eazy cuttlefish to keep they are more picky when it comes to food, I have had them once when I worked for the NRCC. Let me know if you are able to find some.
Salinity would be around 30-32, Temp around 23-25C. The tank needs to have a lot of surface area and be around 18-24in tall they mostly "walk" on the bottom so you need a fine sand bottom with manybe a rock or two. I've found that they prefer live grass shrimp, you should not feed them just fish they usually do not eat them, you should also supply live mysid shrimp. Also they have a really short life span of around 6 months from what I've seen.
I got mine through luck. They just don't show up that much in the hobby. Generally, TONMO'ers don't recommend their collection for the hobby because not enough is known about their numbers.
Salinity would be the same for both species - around 30-33.
BTW, salinity and specific gravity are kind of two different things. Specific gravity is written with the decimal - 1.025
Salinity is written as a two digit number - 33
At least on group has been able to breed them in the U.S. and that would be the Wiakiki Aquarium, and they are very protective of them and do not give them to other Pub.. aquariums. Several people have tried an failed. When we had them at the NRCC we where able to raise them from eggs that we got from the Waikiki Aquarium, the adults showed mating behavior but never laid eggs. In order to mate them you need a group which when they come into the aquarium trade in the U.S. there might be one or two at a time so its hard to get a breeding group. Also the price of them is high unless you find someone who does not know what they are. One importer I know that has had them from time to time sold them for $300 each. Its one of those animals that until someone has been able to breed in captivity should not be kept. I have been looking for some for over 2 years and have not been able to find any, and I know most of the big importers. There is one lead that I'm working on now but chances are it will not come through.