A plea deal does not lead to deposition of witnesses. It’s a guilty plea, no trial, no witnesses, no depositions.
The purpose of this plea, which was written by the prosecutors is simply to smear the president with the appearance of campaign violations. Something they could never prove in court and is arguably not an actual violation of campaign law.
Cohen is in deep shit with his fraudulent attempts to shore up his taxi cab medallions investment and was strong armed with a potential 50 year sentence to agree to sell out his client with this smarmy paragraph in the plea agreement for the media to bleat about.
Of course not, it leads to a pre-sentence report upon which the judge will rely to determine the correct penalty under the Federal guidelines, which is basically a point system. The defendant, in this case Cohen, literally gets "good points", if the U.S. Attorney states that he was cooperative. That cooperation in this case will involve disclosure of something which would implicate others, including Trump in a crime.
Thanks for that clarification.