I am now wondering how would I connect the WD MyCloud to the network as it only seems to have usb 3.0.
You have the wrong device or the wrong specs.
WD My Cloud is an ethernet device..
Please read the specs in full.
http://www.wdc.com/wdproducts/library/AAG/ENG/4178-706288.pdf
It has.. and I quote
Gigabit Ethernet
USB 3.0 expansion port (x2)
The USB are expansion ports.. ie you plug in a second hard disk for backup. Or more capacity.. You do not plug it into a computer for USB connection.. that will not work.
I really like the idea of having 3Tb of storage mirrored
IMHO.. and it is just that..
It is far better to buy the single disk version.. and plug in a My Book of the same capacity and run automatic backups.
If you think Mirrored drives = backup.. the answer is only partly..
Mirror protects from a failed drive.. It has no protection whatsoever from somebody accidently deleting their photo library.. and then thinking.. can I get this back from the mirror.. answer NO.. you do not have a backup.. and therefore it is cheaper and better to forget about mirrors.. and buy the single disk version. Also buy a USB drive and plug into the my cloud to run backups.. these are real backups and the disk can be swapped for even more secure storage offsite.
If you do want mirror buy larger NAS with 4x drives.. so you can use Raid 5 or Raid 10 or many other of the superior methods.. the efficiency is much better.
being able to access it over wireless or externally over the internet which this seems to offer
WD My Cloud plugged by ethernet into a Extreme or Time Capsule. will do this well.
Do you have extreme or TC.. as you seem to swap terms as if they are the same.. the TC has internal disk and AE does not.. also what model are you talking about. Gen1-5 and Gen6 are very different in the AE specs.