Participant observation is a fancy way of saying immersion in a culture. Some engaging in participant observation still allow personal distance; others are detached to allow for non-biased observation, recording, and synthesis of data.
Informal interviewing, asking questions in a native tongue/language, is the most efficient way to gather data/information. Interviews should be informal with non-threatening questions. Once comfort levels are established, questions can become more “personal.” Asking and understand in the native tongue is very important; when translating it is important to preserve the essence, meaning, and understanding.
Structured interviews are much the same as a questionnaire, anthropologically speaking.