Can I protect my USB hard disk by a firewall, and how can that be done? Can I partition my hard disk (c:) with another operational system with no access to the internet help (use this partition to access the external hard disk? Any ideas would be brilliant

As long as you have an up to date firewall, antivirus and anti spyware p[rogrammes on your computer they will protect your USB drive too. Obviously scan anything you download before putting it on your USB drive. Hope this helps.