Thanks for the info, Thales...
The injured cuttle seems to be doing better--it is more active and looks a little better.
As for sexing, I am just guessing based on coloration and behavior. Of the four, there were two larger ones that would display the black "male display colors", and the other two were smaller and remained shades of brown. Of the two that are left, I am pretty sure that one is the largest (presumed) male, but I am not sure on the second one. It has stayed tan/brown since it was separated from the other cuttle, so I am not sure at this point.
They are being fed live Palaemonetes vulgaris shrimp, free choice. I originally turned 100 of them loose in the tank with the cuttles, and there are still quite a few left. I have several hundred more waiting in a separate tank as well. I am also trying a few thawed PE mysis and krill a couple times a day, but the cuttles have not been too interested yet.