WD TV live hub sata spec and others - replacing damaged drive

Hi there, I’m about to replace the 1TB HDD for this unit as it’s not working anymore. I guess that I have 2 options:

Buying a like for like, which would cost around A$130-140

Buying an external 2TB slightly cheaper

I guess that the first one would be a faster unit as it uses SATA 2 (is sata 2?) and the external is a USB 2? might there be a performance issue when playing high resolution movies from external hdd?

or on the contrary, the speed on both would be enough for any movie, and in this case, the extra space on the 2TB would be better?

How does the power management for the hub work when the unit is off, within the network, as everytime I look at it from PC, the drive is available, eventhough the unit is off? being on all the time might have caused the drive to fail sooner than normal?

thanks for the advice

There are certain features of the hub that will not work at all without an internal disk.

such as?

any info on the speed of the sata2 vs usb2 vs high quality movies and vs the extra space on the 2TB HD?

also any info on the power management as it is usually shown as available within the network?