GSFSC = final Resolution?

I am a beginner regarding the software,
so I would like to know 3 things:

  1. does the GSFSC resolution indicate the final resolution of the protein?

  2. will doing a “homogeneous refinement” several times make the resolution better?
    (if GSFSC does indicate the resolution, and to have tested the resolution seems better, but is it really the case?)

  3. When it is usefull to extract micrograph ?