I've just received an email from Oracle saying I've passed. This forum helped me a lot in this challenging deed !!! The main recommendation (may sound trivial...) to the people who want to get certified is to study a lot and work hard. As for part 1, books suggested in this forum are great (Wiley Mastering Enterprise Java Beans, EJB, 3.0 is one of the best) as for part 2 I'd like to thank and quote a greenhorn of this forum Samuel Rizzo who gave me in this post here
this good advice:"My advice is that you don't try to work with something you can't really understand. Make your assumptions. Document. Focus on the final solution." As for part 3 just try to write down how you achieve better security, performance, scalability, availability, manageability, extensibility, maintainability, reliability in your design. Thanks to all this site's staff, keep up the excellent work. It is important there's a place where people can share their knowledge.