Dell T410 Ram Compatability

I just want to check before I buy.

Any ram that is 1/2/4/8/16GB with a clock speed of 1066/1333, is registered and has ecc will work if I populate all the slots with the same kind.

Is this correct?

Also, why does it say 16gb here :

http://ftp.dell.com/Manuals/all-products/esuprt_ser_stor_net/esuprt_poweredge/poweredge-t410_User%27s%20Guide6_en-us.pdf

but not in the manual, is it to do with a BIOS update?

Thanks