The FBI uses Ben and Rhys to obtain private information so they can then get a search warrant. Even though Ben and Rhys are private citizens, they are acting as agents of a law enforcement agency and as such any information they obtained would be suppressed in court as inadmissible. This decision was from 1984 in United States v. Jacobsen.
Payton's tablet turns on immediately, even though his room is said to have been not changed in six years. Tablet batteries don't last that long.