You can refer below link for various configurations supported for XR11. 

https://www.dell.com/support/manuals/en-us/poweredge-xr11/pexr11_ism_pub/internal-storage-configuration-matrix-for-xr11?guid=guid-1890c6c2-9a2a-4f1a-ac90-1c54a52fc935&lang=en-us 

Below link have cabling details for various configuration

https://www.dell.com/support/manuals/en-us/poweredge-xr11/pexr11_ism_pub/cable-routing?guid=guid-a6c60691-f23f-4fd5-a71a-8e2a4f2c5971&lang=en-us 

Thanks for the info. I am still looking for following info:

-- Is it possible to add Raid on XR11 if system didn't come with it - No Perc (config mentioned NVME only for onboard PCIe)

-- If possible, what components or software i will need to purchase?

-- Skill level of this job. Since I am asking this question, you can tell I am new to hardware side.

Cheers