In most of your examples, go and get are not interchangeable.
It's a long post, so I'll make a start. Somebody else might help out.
'I'll be going out soon.' (I'm simply walking out of the house.)
'How can I get out of that?' (I need to extricate myself from a tricky situation.)
'I'll go back home tomorrow.' (I'll leave here and go home.)
'I'll get back about 4 o'clock.' (That's the time I'll arrive there.)
(More later if nobody else responds.)
BE speakers don't normally use gotten.
Student or Learner