Re #21 - #25.
Yes, the company's officers and agents have to act and speak for the company.
For example, let's say that a company, the We Don't Care corporation ("WDC") is sued and that WDC then files a motion for summary judgment--which of course is pre-trial, and indeed has the hope and purpose of winning without having to go to trial.
WDC will have to show the court that there is no genuine issue of material fact and that WDC is entitled to prevail as a matter of law. To support its motion WDC must present the facts of the case--which in most cases will be, at least in part, by affidavit. The pertinent agents, officers or employees of WDC will submit affidavits over their own signatures, but clearly and expressly they will be testifying relative to the actions of WDC, the corporation. The caption of the case--Boston Horseshoe Company vs. We Don't Care, a corporation of the State of New York, . . . case number 16-5476 (etc.)--will be atop the affidavit, and it will show that WDC is the party.
This affiant (corporate officer or responsible employee) will be testifying for--i.e., will be the mouth of--the corporation.