Best Practice for RAID Configuration fo Cisco UCS C420 M3.

I have Cisco UCS C420 M3 Rack Server.

The server has 2 Disk Controller (RAID Controller) and each controller manage 8 HDD (Total 16 HDD).

I have 2 kinds of HDD capacity, 300 GB and 600 GB.

for 8 HDD before, there are 3 x 300GB and 5 x 600GB that manage by 1 Disk Controller.

Our system need RAID 5.

So, I want to ask you about:

1. Best practice for RAID configuration for 2 disk controller and 16 HDD.

2. If I have 4 Virtual disk, can I combine all Virtual disk into one Datastore??

Thank You all.