hi travbug, As far as I know Inti Raymi and Qoyllur R'iti are the most popular festivals of
Cusco, but many of them take place year around. Inti Raymi is a one day festival held every June 24th to worship the sun. It is the second largest festival in South America and Cusco's largest celebration of the year. Qoyllur R'iti is a 3 days festival to worship the APUs and enjoy their ceremonies and dances. It takes place in late May or early June annually in the southern Andes of Cusco.
As your friend said, the Cusco Beer Festival is one of the popluar festival among the
Peru Fesivals. It will be celebrated in the last week of May or early June every year for 3 days in the Garden of the Beer of Cusco. Young people from all over the country will come to participate in this Cusco Beer Festival. National and international musicians play live music throughout the afternoon and night.
My brother has gone to Cusco to visit his friend last May and enjoyed the beer festival, now he is in Cusco again!