To create Conditional Style sheets for Internet Explorer for a Drupal 7 site you need to use the Conditional Stylesheet Module. Download and install and enable the module. There is no module configuration - when the module is enabled you add the stylesheet information to the theme .info file.
The web inspector tools in Safari 5.1 on OSX Lion is switched on and displayed by enabling it in Safari > Preferences > Advanced > "Show Develop menu in menu bar"
Then from the Safari "Develop" menu select "Show Web Inspector" or Option+Command+i
