Was Bill Cosby big in the early to mid 1970's?

Bill Cosby was the first Black Actor to win an Emmy for the TV show I Spy. He was a top earning stand up comedian and had a number of gold records for his comedy albums. He was the number one replacement on the Tonight Show when Johnny Carson went on vacation. He created the animated series Fat Albert. He was instrumental in programs to educate inner city youths and was a regular on Sesame Street. Yes, Bill Cosby was huge before The Cosby Show.

In the 70s, Bill Cosby had the show where he was a high school teacher. I think he also had a variety show, and he had his stand-up comedy albums, but most of those might have been earlier than the 1970s. Cosby recorded one album singing (Silver Throat), with his rendition of Stevie Wonder's "Uptight".

Yes

Yes, that's when he really built his popularity. He even guest hosted for Johnny Carson. A huge accomplishment for a black man in that time.

Yes he was. He did I Spy.