Yes a USB is an External HDD, but it just depends on the size....
Your external USB 3 HDD may work on your old laptop which only has USB 2. Most of the USB 3 will work on a USB 2 if you have the proper speed cable. It will only operate at the 2.0 speed, however.
The SmartDisk USB External 120GB HDD should work with your netbook.
Get an external HDD. Western Digital do 1TB ones with USB and network ports.
The only way you can do that is to buy any external HD case that has either a firewire or USB interface on the back. Install the HD in the case and use one of the two interfaces I mentioned to connect it to your laptop. you get a external plug it in by the cable that is provided into the usb of fire wire por on your pc/mac
No. You will have more storage but performance will not improve.
Google 'Configurable USB Loader Guide'
Please check that your external HDD is USB 2, and find out whether both use USB 2. Also check the cables.
Yes It Is
You don't.
Yes but its only for the internal one not usb hdd.
No.
No, when using the Norton 360 backup, files on the external HDD will not be deleted.