If you hold a B2 tourist visa, you are not required to hold a return ticket; you may enter the U.S. on a one way ticket. However, if you do not have a round trip ticket you may have more difficulty in proving the temporary nature of your stay.
Check the accuracy of all the data on your B-2 visa, including name, date of birth, passport number, gender, and photo. Inform the Consular Section personnel of any errors.
Yes, the CBP, US Customs and Border Protection is the sole authority to permit or deny admission to a foreign national at the Port of Entry.
Note: In addition, the period for which the foreign national is authorized to remain in the U.S. is determined by the CBP, and not by the Department of State Consular Officer.