The Power CMS works in the way you have described. It will insert the content into your db, then using the references that it gives you whatever is updated in the db will appear on the pages where the references are.
This is really designed to handle content of your pages though, not a user bio area. I think that you would be best off using Security Assist along with DataAssist to build out this functionality. Security Assist can create a set of user pages that will allow the user to register, login and update their profile.
You could think of the bio page like the profile page. The main difference is that the information on this bio page will be public. To make it so you can add in the html editing abilities for this bio page you could make use of iRite or HTML editor if you have it. Please post back with any questions that you have and we will be glad to help point you in the rite direction.
