Commitment
Of course you have commitments to your home institution, which is usually your employer. But as a CERN user you also have a commitment to CERN which, as host laboratory, provides the infrastructure and a community for accomplishing our common goals.
Confidentiality
No. If the confidential internal information that you gained is restricted to that group, then it is not acceptable to share it with anyone outside of the group, including CERN colleagues. If you are unsure as to whether information is confidential, it is your obligation to verify.
Disputes between a person and CERN (outside of Ombuds mandate)
The Ombuds' Mandate limits his/her services to providing guidance in the application and interpretation of the Code of Conduct and to providing assistance for the informal resolution of interpersonal issues. The Mandate explicitly excludes the Ombuds from handling disputes arising between a person and the Organization, in particular relating to administrative decisions. Since your case involves a dispute with the Organization, the Ombuds cannot address the matter. Your dispute should be handled in accordance with the review and appeal procedures set out in Chapter VI of the Staff Rules and Regulations and in Administrative Circular No. 6 ("Review Procedure").
Diversity
No, this is not what is meant. Remember that diversity is not just limited to ethnic minorities and women. You should select the best people for the job and you are encouraged to select team members with a rich set of ideas, different backgrounds and perspectives to contribute to the project.
One way to encourage diversity is to ask for, respect and consider the different views of your colleagues. By appreciating the differences that exist amongst your team members, you are creating an environment that promotes collaboration and builds effective teams.
Expressing personal opinion (CERN policy)
You can express your views when contributing to CERN policymaking, but once policies have been adopted you should refrain from publically expressing views that undermine the policy. If you have concerns about a current policy, it is best to address them through your hierarchy, the Human Resources Department or the Staff Association, a body that has an ongoing responsibility to foster productive staff/management relations and to stimulate dialogue about internal issues.