Basic Graphics Questions , How GPU works and achieves Parallesim.

Dear Experts,

I have some basic graphics questions here, my interest is basically with ARM MALI 400 MP2.

Please provide your inputs

1. Open VG/GL/GLES APIs generates any commands for GPU(VP and PP) to process? Are they defined by Khronous?
2. Is every Open VG/GL/GLES API generates some commands?  Few of them may just configure the GPU registers to set the inputs and GPU state.

   3 .  Does the GPU works like some state machine processing the commands generated by OpenGL/ES APIs?  
   4.   Does Mali 400MP has any Instruction-set like ARM Cortex CPUs? I think few GPGPUs have like NVIDIA, ATI/AMD.

   5.   What happens to Shader programs after they gets compiled? the compiled out put is some instructions for Shader-HW?
          Or some commands OR what ?

   6.How the parallelism is achieved in ARM MALI 400 MP GPU? Does it because we have multiple Pixel processors?

      I am not interested with GPGPU or GPComputing , Interested only Graphics content rendering case.
      I am trying to understand how GPU is performing better than CPU for graphics content creation?
      does GPU do some SIMD instruction execution like DSP?

Thanks,

Ravinder Are