How can I list all of the posts, by author?
This is the sort of feature that one would hope to find in any well designed content management system, which is yet one more thing that Blogger is not. I'm sure that this question came up in the AppsSpot Blogger Enhancements forum, I don't recall that it was discussed terribly vigorously.
There is a solution for this need, though it's manual, and may have to be enforced by the blog owner. Simply have each author assign a label to each post, using his / her name. You, the blog owner, can verify consistent and proper labels, by checking against the Edit Posts menu, which lists both author name and label membership of each blog post.
With each post properly labeled, simply add a labels index - either a Blogger standard one, or a third party one like the Cumulus Multi-Style label index. You could even make your own as part of a custom "Blog Members" gadget.