Chad Singerr, a citizen and resident of country H, conducts a four-concert tour in the United States. A multi-talented individual, Singerr sells tickets to his concert from the ticket booth before his concert begins. During intermission, he sells beverages from the concession stand. Afterwards, Singerr sells Tshirts at the concession stand.

1. Is Singerr engaged in a U.S. trade or business? Explain.
2. If Singerr is engaged in a U.S. trade or business, what income is subject to U.S. tax? When does Singerr pay any U.S. tax? What form does he need to file?