hide cck field not working
You should also have a look at the Field Permissions module, which allows you to control granular permissions per field by role. 

By default, if a user can edit a node they can edit all fields, but Field Permissions allows you to create specific privileges for the field if you need more granular control.

So for this instance, you'd want to enable edit privileges for the fields you want to hide from the anonymous users, then go to user permissions and grant edit permissions for those fields only to authenticated users.  The result would be that the fields would be hidden from anonymous users, but still editable by authenticated users.

You could then use the Forms API as Dan described to make the fields all of a length for anonymous users, or use something as simple as CSS if your theme attaches a body attribute for logged-out users (many do).