your muse character ought to be one who pushes you to think about your own expectations/beliefs about the character and canon events. I don't know about ought to be - but it works for me ;D

Once the creative part is done, you can tidy up the work, you can fix plot holes, you can cut scenes out - and maybe even re-use them in a different fic later. But you can't edit until the first draft is done :D Exactly - if I tried to find all the errors before I got to the end of the story, I'd never finish!