1) In eclipse you create the 3 project and make a pom.xml file for each for the maven management. After this, you should make:
- parent depend on api
- impl depend on parent and api
This way the eclipse m2eclipse plugin will connect the projects to each other.
2) This project structure is only advisable if you will ever need to change the whole implementation of the defined api. It allows you to place another jar with another implementation to the application easily, without modifiing any java code. Of course it's only applicable if you are refering to the api only, through and not the implementation. It can be accomplished with EJB or Spring.
3) I can't think of any tutorials or sites out there, sorry.