When you use the validate internet address tool, it only tells you whether the were any that were not unique, or rather how many were not. Surely it could return a list of the ones that are not unique.
In the Addressing section of the registration dialog box the internet address field is the first field that you tab to, however if you tab to the internet domain field and add the internet domain it will build the internet address for you from the first name, last name and ...
The internet password option is only accessible if you click on the password option button in the registration dialog box. Also it is not very obvious and so many people miss selecting it. Please move it to an area where it is obvious.