Answer to Question 1
Answer: When a speaker is unknown to am audience, the speaker does not have the credibility that comes from being known and trusted by them, or by being a recognized expert in the field. The speaker does, however, have a relationship with the VP of the company where he is going to speak because the VP is his former employer and mentor. Mentioning this strong affinity with a source known and credible to the audience will help convince the audience that John is trustworthy. The speaker should also mention key credentials in relation to his speaking engagement, namely education, experience, and expertise. The speaker will also add to his credibility if he presents an unbiased point of view, organizes his ideas logically, and supports them with good research and sound reasoning. The speaker can also add weight to his ideas by citing authorities and experts in the field.
Answer to Question 2
Answer: You will be more effective when trying to persuade an audience if they believe you to have expertise and to be trustworthy, based on your knowledge, character, reputation, and behavior. If you are unknown to your audience you can try to establish credibility in a number of ways including getting to know your audience, introducing yourself effectively; and presenting your ideas effectively. Credibility is very important for capturing an audience's attention and persuading them to listen. Yet despite its importance it can be easy to lose. If a person with credibility makes statements that turn out to be false, or makes promises that can't be kept, credibility can be lost. It is also true that credibility alone isn't strong enough to change the mind of someone who is deeply interested in an issue. Additional persuasive techniques will be needed to successfully persuade an audience, but having their trust is a very valuable thing. It is certainly of enough value to strive for, despite the fact that this is not done overnight. Credibility is also not a black and white thing; it's not a matter of complete trust or complete lack of it. So it is certainly worth some effort and time to try to establish credibility.