ACF can do everything on the list except 3. It does not lock posts. This would need to be done and detected by you and to be honest, I couldn’t tell you how to do that.
For those I’d start here:
http://codex.wordpress.org/Function_Reference/wp_set_post_lock
http://codex.wordpress.org/Function_Reference/wp_check_post_lock
Then all you need to figure out is how to unlock the page when the user closes the page or navigates away. More then likely you’d need to fire an ajax request onunload.
