How many disks for Raid 0

Can you put 4 drives into this at Raid 0 in order to get maximum performance across 4 drives? Or is Raid 0 just across 2 drives maximum? Also, do the disks all need to be exactly the same model or same sizes? Can they all be totally different size drives?

Well this is really for a high speed network only so not internet speeds. It seems like the read and writes would help performance under those circumstances, but I am eager to learn if that is not the case.