Hello, jabbarsh.
As your questiones, the answers is following:
1) Is it possible to add SSD or 2.5 SATA HD instead of SAS which is very expensive?// yes, you can
2) Can I create a raid 0 configuaration with the SSD?// of course, it support Raid 0.
3) How much is the storage capacity for each SSD?// the total storage is 8 TB, so if the eight SSD is the same, it will be 1 TB for each SSD.
