1. To head off an issue
This is a footballing metaphor. It's used to mean you deal with an issue quickly and efficiently to prevent any problems in the future.
2. to press your case
This is originally an idiom from legal English. In this context it means to express your opinion forcibly so that other people take notice.
3. One team, one dream
A slogan, whose words are chosen because they sound good. Meaning that everybody who works on this project or in this organisation has the same aims and aspirations as each other. ( A rather optimistic statement from a large multinational company!)
Hope this is useful to you.
Student or Learner