#1 Why did the DOJ and FBI want to wiretap Carter Page?
According to the analysis at The Conservative Treehouse here:
the FBI requested FISA approval under Title I, which allowed them to surveil anyone Page came into contact with or was associated with, including everyone in the Trump campaign.
Also realize that Page was not a very well known entity in DC, and Judge may not have know he was minor player on Team Trump, and although Trump was real target, FBI never raised Trump issue with FISA judge.