Did mozart know/speak italian?

if he did how did it impact his life?

what operas proved he can understand italian?

Yes, Mozart spoke and knew Italian. This impacted his life because, during that time period, it was very common for operas to be written in Italian. So, he gained popularity. Some operas were "Don Giovanni" and "La finta semplice"

Yes and no because if you know the vocabulary used you will understand it and go faster but you might not need it