Good start. My comments:
1. There's no way to read /wordpress/page/2 sorted by last comment date.
2. There's no way to read /wordpress/page/2 sorted as usual, unless the reader edits the URL directly.
3. If the Main Index template has a Recent Posts widget (or something else similar), the widget lists all the posts on the blog.
4. Trackbacks and pingbacks appear as unintelligible replies. For posts that only have trackbacks, the post's page has no "#comment" anchor id, so the "View all replies" link doesn't work.
5. sbc_displayLastComment doesn't apply comment_text filters.
6. If a commentator posts a tirade.... well, let me say it ain't pretty. ;) Perhaps the comment excerpt is better; and then again please apply comment_excerpt filters before echoing it.