Is it true that The Rockford Files was tailored after Maverick? James Garner's other show? Plus, was Rockford kind of like a Sherlock Holmes type, and Angel was like his Watson?

well, they look similar, but the characters were prety different

James Garner said in his Biography that Rockford was basically Maverick retooled in the form of a PI in the 70's Watch Maverick and then Rockford. James Garner is playing the same role, just in a different setting.