What flash will give me results like these?!?!?

I hear you Curtis... just in the past I always read and understood that to bring in more background light etc in a dark (esp club environment) and low light lit place, you have to up the ISO and shoot wide open?

I got baffled when start seeing people shoot with F4 or 5.6, again surely that lessons the amount of light coming through? Or is that literally for the flash to work harder?

On another note, when the flash works harder, has that got anything to do with what power you set the flash at? I take it that it tends to work with bounced flash more than direct right? As only the first set of people will be lit, whilst the people behind will slowly fade out? Or is that when you change the aperture?

Look at a fill flash photo as two exposures combined into one: One for the ambient, one for the flash.
Ambient lighting is controlled by ISO, aperture and shuttertime, flash is controlled by ISO, aperture and flash power.
If you close the aperture or lower ISO, less ambient will come in (unless you pick a longer shuttertime) and the flash will have to work harder.

Flash is controlled by ETTL mostly, so within limits, flash exposure will take care of itself regardless of ISO and aperture.

Generally speaking I choose an aperture based on the DoF I need, and set a shuttertime to allow enough ambient. (I'm at high ISO anyways, so don't have to choose there )

only issue is with slow shutter speeds, we get hand shake, but i take flash will freeze the majority of motion

If there is no ambient light hitting the subject,you won't see motion

You might want to have a read in this thread as well.