How to have a content type that displays a title, a description and a list of feeds imported from an external URL such as blogspot?
Drupal creates 25 node of "blogger" type, that are my feed items, but I don't want this.


There is a difference between attaching an importer to a content type and selecting a content type on the node processor. The first one is meant as a sort of "container" - you'll need to create nodes of this type in order to import content. The content type select on the node processor is the type of nodes that Feeds will create when you import content. Make sure that these two settings are always different.

So you need to make sure that you have two content types:


One content type - called "blogger" for example - is the content type that you attach the importer to. This setting can be found under "Basic settings". This means you need to create a node of this type in order to import content.
The second content type - called "blog item" for example - is the type of content that you want Feeds to create. Select this content type on the node processor.


When you now create a "blogger" node and provide a source - in your case an URL since you selected the HTTP fetcher for your importer - Feeds will create nodes of type "blog item".

In order to show the blog items on your blogger node, you'll need to create a View and find a way to display that View on your blogger node. One way of doing that would be using a block that is only shown on your blogger content type.

If you want to have a head start with this, I recommend to install the Feeds News module (this module is included with Feeds). This demonstrates how to use the attach to content type feature. It also includes a View for displaying the imported items (though on a separate page).