Don't know, don't use Safari much. In FF, double-clicking a
tab causes it to open in a new window. Not sure where one could click in the 'tab bar' as tabs expand/contract horizontally to fit the width of the window once you have a certain number created. There
is an icon to click on that will create a new, empty tab.
I would assume you can also command-click a link to have it open in a new tab?
Later, yep, FF does the same thing. You just have to have fewer tabs open so you can actually have some empty space in the tab bar (about 4 and less in the window I usually use). Could be a quicker way to create a tab but if you're going to have to type in the url, you'll probably also already have your hands on the keyboard.
