primary sources are from someone living at that time / someone who directly experienced the event they are talking about
secondary sources are people [who did not experience the event] writing about an event after it occurred. These people were not directly involved in the event, making them secondary (you can think of it as second-hand information) sources.
tertiary sources are essentially sources identifying primary / secondary sources (they're a reference for resources)
What I think he means is that the bystanders knew what was happening but didn't stand up for it. They didn't fight for the Jews rights. But in my opinion that statement is wrong since anyone who stood up or defended the Jews would be killed.
No, it is false that traditional grammar is still completely based on the Latin model, since many of the ways in which grammar has shifted have noting to do with the original Latin forms.
