For CB Blogs? They're linked to the profile the blog post belongs to.
Can only blog headings be made visible to site visitors, and additional blog details to registered users.
Not without modifying the template files.
How can a group member display and search blogs created by another user?
If you use Joomla model for CB Blogs then they can just use normal Joomla search. If using the internal model then there is no searching outside of profiles. So if you need that functionality I recommend configure CB Blogs to use Joomla articles for storage within CB Blogs > Parameters > Blogs.