Yes, there's a Critique Request subforum that opens up after you've participated for a bit. I'm not sure how long or how many posts, but you should be able to see it soon. And yes, a new thread for each chapter. I just wouldn't post the whole thing at once, and be patient.
I agree, if I could post 160 characters at a time I would probably have a lot more comments. I was a Reddit junkie until recently, but there is no sense of community there and no matter how hard I tried, no way to foster it, not in my experience anyway. *fingers crossed* I'm looking for a good community of persistent personalities if such a thing exists anymore.