Can Green-Flame Blade or Booming blade be used when invoking Charger feat?

Where did the GREEN FLAME originate?

Green-Flame Blade no target creatures

If I cast Green-Flame Blade and use Divine Smite, does the smite apply to both creatures?

How would Fire Elemental Affinity apply to Green-flame blade

Are Booming blade and Green-flame blade part of the attack action?

Can Booming Blade and Green-Flame Blade used with a whip?