User Theme Settings File blender has some presets by default ( xml files )
and user can save his own settings for theme ( Save User Settings )



now, 3 simple question

1- is it possible to create an custom xml file to load when blender will open ?

2- where is saved settings file ?

3- where is default blender theme file ?
1-Yes,You can import edit your theme or import one from and XML file then press Save user setting.

2-Blender save user setting here "C:\Users\Username\Application data\Blender Foundation\"

3-There no file for the default theme.