Re: Member List
=== Is it possible to display complete details and add additional fields tabout the member including a photo? ===
Yes. The avatar upload will be the photo of the member.
https://codex.buddypress.org/getting-started/configure-buddypress-components/
=== and I’d really not want them to be a member of WordPress. ===
BuddyPress is a WordPress plugin that uses WP functions in many cases including being added in the wp_users table. If you don’t want the members to be WP “users” in the main site, go multisite and install BuddyPress in secondary blog.
https://codex.buddypress.org/getting-started/install-buddypress-on-a-secondary-blog/