Have websites comments appear on facebook page as wall posts.

Nathan,
No, you can't do that. It'd be nice, but could also get unorganized quickly as Facebook likes discrete areas for things. If a comment is about a specific page/URL, then it should be posted to that page. If you have a long thread on your Facebook Page that's really about a URL on your site, it can be awkward and the conversation could easily go astray with other postings.

I can't always speak for Facebook's intentions, but I know how they work after dealing with them for many years, and they really push the 'branding' of a Facebook Page. If you mix that too much with a live site, then Facebook can become secondary.

Hope that all makes sense and answers your question,
Alex