I keep seeing, on almost every forum, people complaining about not having a target's target button. I myself, at first, was this way.. However It is in the game and so there is no need to complain about it. They just didn't tell you how to do it.

How to: Target's Target
Target's target allows you to say, select a the tank, and then press a button to automatically select what he is targeting. By default this is " Alt+T ". If you wish to change this, you can. just go into options and at the bottom of the windows there will be a tab labelled "Key bindings" go to it and select targeting. close to the very bottom is target's target. feel free to set it how you want.

How to: Focus Target
Focus target is a great feature for everyone, but mainly healers. Focus target allows all abilities to be directed to a pre-selected target. So if you are a healer, you want to have your tank focus targeted, so when the time comes you can just hold down the focus target button and hit your heals. By default this feature is not even turned on.

To turn this feature on you go into your options and.. (oops forgot where?) well you should be able to see a box that is labelled "enable focus target". Make sure you select that.
Once on, you may not use this handy feature. By default "alt+f" selects your focus target and holding down "f" and using an ability will direct that ability to your focus target. Once again, you can change this in the key bindings -> target area in options (i know classes that use the cover feature, have F for cover)

I hope that is easy to understand... and I hope it helps you out!