HTMLValidator results should be almost identical to the W3C validator.
However HTMLValidator cannot validate HTML5, although the W3C validator calls out to validator.nu for this.
Yes, more information is available on the HTMLValidator Open Source Page
Use 1.2 or later for 10.7/Lion support
Not currently (sorry)
HTMLValidator should now be uninstalled.
The main ones do and the minor ones should too. (Hopefully)
If you use HTMLValidator to find a page that fails please get in touch, we'd love to hear from you!
To contact us with a support issue please email: