As one of those who've discussed 'characters going rogue', I have a few comments:
1) Copyright theft involves the stealing of words, not of concepts. If you can write a better version of Star Wars, set in a completely independent universe, then more power to you. Writing inspires writing. If authors couldn't build on the word of others, then there would still only be one vampire, one zombie and one spy novel.
2) As I've stated before, your character know your story better than you do. You [often] have a predetermined destination in mind, but your characters will know whether that destination will work or not.
3) I'm not sure where the 'theft' accusation comes from? Because you changed your story mid-process? Because you included the ideas of characters 'acting out' as a plotline? That you credited someone else for giving you an idea? So far, I'm not seeing any potential problems from any of these.