Good morning,   What information are you looking for when you ask about the "kind" of drives and firmware? I can say that they're all SAS disks. Like Sam had mentioned, they're all going to need Compellent firmware. You'll need to contact sales for full details on part options for purchase. There are a lot of individual part numbers listed in the database and without knowing what information you're looking for, I'm not really sure how to answer your question.
We have a Dell Compellent (not sure exactly what Series, but it's a model EB-2425) that currently has 12 disks in it - 6 x 146 GB 15K RPM disks (one of which is a spare) and 6 x 1 TB 7K RPM disks (one of which is ALSO a spare). According to the dialog from "Help" > "Licensed Features", we are licensed for 16 disks, and currently have 10 "managed non-spares in use". We would like to populate the remaining six drives allotted to us - can we just go out and... buy disks, and put them in there, and our licenses will transfer over? Do these licenses apply to any ol' disk, or are they size-specific? I'm assuming that I will have to buy Dell-branded disks?
Dell Compellent disk licensing?