When you want to create a custom item template in a repeater you have to readthis article. In this article the css-class and the html depends of the content of the data collection. So you want a different ItemTemplate for another row.
In de web.config of a (web) application it is possible te configure the customErrors element. Mostly for development I want to see the details of the errors so I can fix these quickly. But when the application runs for end-users I want to be informed about these errors and the users sees a friendly message "there is something wrong, this is registrerd".
