How does the Pratt & Whitney F119 achieve its features? The Wikipedia article on the Pratt &amp; Whitney F119 that powers the F-22 says the following:


  
  The high pressure and low pressure turbines are single stage and counter-rotating, thus shortening the engine and saving weight.
  Turbine: Counter-rotating 1-stage high-pressure, 1-stage low-pressure turbines
  Type: Twin-spool, axial flow augmented turbofan
  


We also find:


  Thrust augmentation is using additional fuel in a turbofan's cold bypass air only, instead of the combined cold and hot gas flows as in a conventional afterburning engine.— Afterburner





What's the benefit of lighting the bypass air compared to relighting the exhaust? Wouldn't the cooling benefits of the bypass air be lost?
Does that mean that the F-22's "supercruising" could be "augmented"?
How does by counter-rotating the two-spools, the engine becomes shorter and lighter?
How are the turbines counter-rotated?


While the answers are probably buried deep in the Integrated High Performance Turbine Engine Technology program, hopefully some educated guesses can entertain my curiosity.

My only guess for 4. is the use of aggressively curved and converging stators, which would otherwise stall a normal none counter-rotating LP turbine. Or perhaps the lack of a stator in the turbine section, since it's a single LP stage, which would also answer 3.
The afterburner is aft of the gas core of the engine in the jet pipe and bypass air from the fan would have already been mixed with the exhaust gases from the core prior to passing through the afterburner flame holders.
Supercruise is by definition supersonic cruise flight without the use of afterburning, so augmentation would not be in use here
Counter rotation of the spools reduces net torque from the spools upon the structure of the engine requiring less metal and therefore lightens it.  The length of the engine is reduced by making use of a single stage, high efficiency turbine rotor per spool as opposed to multiple turbine stages per spool, which would make the hot section of the engine longer.