Boleto (Boleto Turístico General, or BTG) is the admission tickets to some sites in around Cusco. If included sites matches with your plan, it is wise to purchase the Cusco Tourist Ticket.
In the street stalls they sell Alpaca sweaters, which are always made of baby Alpaca. But in almost all cases they are not baby Alpaca, even not Alpaca. Mostly they are made of Polyesters or acrylic. Alpaca sweaters should cost you at least 40/50 $. If you bargain with the price and be able to bring the cost down to as low as 20/25 $, then it is not Alpaca.
Many people visit Cusco looking at the calendar of Cusco festivals. Festivals at Cusco are colorful. Processions, parades, dance, handicraft fairs - all these happen during most of the festival days. Some of the festivals, like Inti Raymi, whole city is engaged, while thousands of visitors from different country joined with them. Here is a list of some important festivals, and their time in the calendar, so that you can choose your time to visit Cusco.