The three essential qualities of a speaker are sincerity, friendliness, and authority true or false

Yes, a professional speaker would need characteristics as you have listed; sincerity, friendliness, and authority because no one wants to hear a speaker who isn't friendly, honest, or confident. Speakers must be relaxed, show complete honesty, and make sure they aren't rude because a speaker would expect to have all types of audience, even those that may oppose what the speaker is saying. 

Overall, the answer to your question would be true. I hope I was able to help you with your question. :)

This is true! :) the three essentials are Friendliness Authority and Sincerity