Yes. All the time. Right down to the very second I post a finished chapter of a story online... 6v6
Weigh options. Try things. If you really think a story might work better if written a different way, jump in and try writing it the new way. At least outline some prospective scenes. I've deleted dozens of pages of script in favor of new directions that turned out better than I hoped; it happens to me all the time. To be honest, it really just keeps happening until I get a story I'm more or less satisfied with.
Definitely. It hurts, but no single character is more important than their story. They can always be moved to a new project; no sense destroying the existing one for their sake.
See the above. This actually hurts worse than removing a problematic character; cool characters and events and names are nice, but when I fall in love with the way I've written something I fall HARD.
Still, there are more important things. If nothing else, you can save the old writing in an old file, and resume work in a new file. I'm doing something similar with a novel I'm trying to rewrite; the first draft was borderline nonsensical, but the writing in it was so good I can't bear to delete it. It's just gonna stay in my computer. ^^;
Well, obviously, no. But with art, it's hard to tell whether you're editing to improve or just editing for editing's sake...usually, the way I figure out whether I'm actually making progress is by determining how close I'm getting to a concrete ending.
There's a comic I'm scripting right now; it's been chopped up and rewritten and half-deleted over and over. But I'm definitely closer to the ending than I ever was before. Just keep swimming~