Raid 5 question

[nightrider1470]

I have just bought a 5 bay hard drive enclosure and plan to use Raid 5. My question is can I install 2 drives say then just keep adding drives when I want? or will I need to install all 5 hard drives at once?

Thanks!

 

[nightrider1470]

Can you mix the drives? This is the enclosure here http://www.sharkoon.com/?q=en/node/1809

 

[nightrider1470]

On the back of my raid enclosure it has raid options. Am confused to what the combine switch does? - Bottom right on pick!

is it possible to have it setup with 4 x 4TB drives 2 drives mirroring each other?