DL360 G5 Server Smart Array Controller upgrade

[ChesterT]

Hi

I have  HP ProLiant DL360 G5 Server with HP Smart Array P200i/64MB v1.20 Controller  (RAID 0/1/1+0)

I used this website http://h18004.www1.hp.com/products/quickspecs/productbulletin.html#spectype=north_america&type=html&docid=12476

as a guidance 

and I am not sure what parts I should order to upgrade it to HP Smart Array P400i/256MB Controller and have ablility to use 4 SAS hard drives and RAID 5

Now I have only one SAS cable going from drive board to the P200i controller (I see another plug on the drive board but there is only one input on the controller) 

The P400i have two inputs so I assume I need to order P400i controller and SAS cable? 

399550-B21   HP Smart Array P400i/256MB Controller

408763-001   HP Mini SAS Cable for DL36x G5

Could you help me and confirm that above parts will work? Also do I need to order anything else to make it work with RAID 5 and use 4x HDD ? (I see option for Battery-Backed Cache Upgrade but not sure if it is mandatory or just option)

Thansk you!