Misc: name the fat, rich detective with a passion for beer, food and orchids?

Questions

This brother act had 4 #1's in 1970...?

This co-star of "The Carol Burnett Show" hit #1 in 1973...?

This group song the 1978 #1 "Baby Come Back"...?

This man sang lead for the 4 Seasons comeback #1 hit in 1976, "Oh What A Night"?

This singer's "Escape (The Pina Colada Song)" was the last #1 of the 1970s...?