Do law enforcement officers have an implied license to conduct a 'knock and talk' in the curtilage of a home?

QUESTIONS PRESENTED Question 1: Do law enforcement officers have an implied license to cross the clearly marked and defined curtilage of a home to conduct a "knock and talk" where the homeowner has taken numerous steps to ensure privacy and security, thus giving express orders to the public and for private citizens not to enter? Or, in the alternative, does such an action violate the owner/occupant's reasonable expectation of privacy as guaranteed by the Fourth Amendment? Question 2: Does counsel provide effective assistance, as guaranteed by the Sixth Amendment, when he fails to investigate obvious avenues of merit involving serious Fourth Amendment violations of seizure and detainment within the curtilage of a home, flagrant police coercion, and warrantless search--issues that would have led to a different outcome at trial? i