First of all, there is nothing preventing you for using usernames as realnames, as you can use spaces by default in username, but you got some options tho.
You could create a author field your self on the node type, however this forces you to type it in manualy.
You could make a template for the nodetype, printing the profile field yourself.
I will thought encourage you to have a look at either views (http://drupal.org/project/views) or panels (http://drupal.org/project/panels), which gives you a lot of control of the output.
If you are new to drupal, start with Views, this will solve your problem almost out of the box by override the node/% page.
With panelizer (http://drupal.org/project/panelizer) you can define default layouts for each nodetypes, using fields of choice.