That's a really good anology. There are "whats and ifs" in there too, though, because the one writing the story could always just erase the character and begin anew if he wasn't pleased, or he could simply write things that go against the character. But yeah, I suppose the CHIM person could have some powers on his own, but he wouldn't be able to use them in a manner that affects the world to his will. Only to the writer's (the godheads) will.
But as for Vivec gaining CHIM after the games, Vivec says (after the main quest) "our powers will fade". His powers wouldn't fade if he had the kind of CHIM that is generally viewed as CHIM (e.g. not my view).
I'm going to respond to the last part first and the first part last, because that's the order the responses occur to me.
When Vivec says "our powers will fade" I presumed he was refering to the god-powers the Tribunal got from tapping the Heart, and not to CHIM. I think those powers did fade, but I don't think his CHIM did.
What would you say your conception of CHIM is?
Earlier you suggested that CHIM had something to do with one's relation to multiple timelines, as in comprehending all possible timelines. I think that adds unnecessary confusion to the issue, and would appreciate it if you could state your views on the subject in a more simplified form.
What would you say the general view of CHIM is?
Those that are taken by the loveletter tend to think CHIM is some type of relation between a dreamer and his/her dream. There seems to be some disagreement on whether or not the dreamer knows he/she is dreaming, and whether that makes a difference.
Okay, now to respond to the first part, second.
It is true that the character cannot act contrary to the will of the author, but that might be a feature of the example which shouldn't be attributed to what it's (imperfectly) representing. What if one of your characters takes on a will of its own? Are you sure you could erase it? Even if you deleted every instance of the character's name in your story, will the character really be gone? It's not clear to me what the answer is.