NAS Expansion

MY WDWE1TB (Western Digital World Edition 1TB) is running out of space. I would like to hear your advice on expanding the NAS space. I believe there are three options:

Option 1: Replace the 1TB with a larger WD Green HDD bare drive.

Q1: Is there a size limitation? Can I use the 3TB Green available on the market?

Q2: Is all I need to do to take out the old drive and drop in the new drive and wait for the unit to initialize the new drive?

Option 2: Buy a new My Book Live 3TB as the second NAS on the LAN.

Option 3:  Attach a Seagate GoFlex 1.5GB USB 3.0 drive to the USB port of MY WDWE1TB. Will the read/write speed of USB drive attached on the MY WDWE1TB be the same as MY WDWE1TB itself?

I attached the USB drive to the Gigabit Belkin router before. The read/write speed was horrible. It was the reason why I planned to attach USB drive to MY WDWE1TB.

The current speed of moving a 6.15GB file from a local drive to MY WDWE1TB is about 14.5MB/sec.

Since I have already had the 1.5GB USB on hand, the option 3 will be the most economical way to expand the NAS space, if the speed is not the issue in this setup.

I would go with the new My Book Live 3TB, that way you can take advantage of the new features. Check the link below for more info.