Thanks for the comment.

Re (1), there's no contradiction between "most of what we come to know we do by being told or by instruction" and "we come to know because it is true". Maybe the language is not clear but basically I got to know that water boils at 100 degrees C because I was told this fact by someone who is an authority (say a teacher?) - or by consulting a knowledge source (a book?)... the point is, these facts I don't get to know by experience!!

This should also answer (2). I don't "learn" from other (ordinary) people, but people of authority, or knowledge sources that have been "approved" (books, reviewed and approved results, etc.)

Re (3) yes, language is understood in context. But a 4-year old can handle it... now the history of the conversation is in my opinion not that much of an issue, because I might start a conversation with a 4-year old that never saw me but I bumped into in a zoo.... the conversation will go well and no problem. Why? because we share the same COMMON (sense) background knowledge about the world we live in. That is the key!

Best...