Hi
The issue of copyright of the photos may be a bit more complicated, I think that the photos taken in England would be governed by English copyright law and the photos taken in Australia by Australian law. In Australia copyright expires 70 years after the death of the photographer, and I believe that photos taken before 1st Jan 1955 are out of copyright. I think it means that just because you own an old photo that has been handed down that you don't own the copyright.
http://www.copyright.org.au/find-an-answer/On the other hand if you have your own website then the material on that website would, I believe, be your copyright. Unfortunately many people think that anything on the internet is free to use. if others copying your material is of concern then it may be worth getting legal advice re copyright, and your options if someone does download, before posting your material.
One thing to keep in mind re family photos is that a number of 'originals' may have been printed off the negative so other branches could have the same photo.
I haven't tested it but the snipping tool on Windows Vista and Windows 7 enables you to capture what is on the screen so probably bypasses the disablement of the right click, a watermark might be the way to go.
Andy