When I click a link say via email, or shortcut or whatever, I want it to open a new tab not take over an existing tab or open a new window.

In firefox, this is available by default. You do not need to add a tabbed browsing extension in order to do this.

There are three ways to do it in the default firefox configuration:

1. Hold down CTRL while clicking on the link will force it to always open in a new tab. (This is very similar to holding down shift to make it open in a new window.)

2. Right click on the link and select the the appropriate option (not very convenient, but works).

3. My personal favorite: CLICK THE MIDDLE MOUSE BUTTON ON THE LINK.