I would like to decide what content type users can create into a space. Is it possible?
I would like that my space called "Recipes Repository" have only content with the type: "recipe". When an user click on the create content link, I want that the default or unique content type was "recipe".
Not out of the box, but with some customisation and configuration, yes, it's possible.
You could override the CreateSpaceDialog class and the configuration for the 'createSpace' dialog. In the finishImpl() method you could detect whether you are in the "Recipes Repository" space and if you are use your custom content otherwise use the default type.
I will not do this change due to I don't want to change the source, all my changes will be extensions and configuration. In this way, when I update the Alfresco version I will not loose my changes.