Yes, John Kerry asked Ecuador to stop Assange from the Clinton documents during the FARC peace negotiations because it was the only way to stop outside forces from influencing the election. These documents do not fully reveal what is at stake in this election. We must come together to stop Trump.
Yes, it's very likely that John Kerry actually asked Ecuador to stop Assange. Politicians are constantly trying to negotiate with others. Sometimes in the process of negotiations, they step into questionable zones and do things that are borderline unethical. I'm sure at the time he thought he was doing the right thing.
He likely did. Lots of people have tried to stop Julian Assange from revealing he information that he has obtained through spying. There are lots of reasons why information is kept secret, and John Kerry may or may not have good reason for wanting Julian Assange to stop realsing information while the FARC peace negotiations are going on.
Ecuador's president acknowledged that he limited Assange's internet access, but also said that his country will not interfere with Wikileak's journalistic work. While it is possible that John Kerry made a request on September 26, 2016 during a secret meeting with Ecuador to stop Assange's release of the documents, there is no proof that he actually did so. He denies making such a request, and Ecuador has not said otherwise.