Language Questions

Who is answering the question (SPEAKENG) about the English level for children (between 5 to 16)? Are the parents? are children reporting their level of english?

Assuming you are referring to the ACS data, generally the questionnaire is completed by a single individual for everyone in their household. The Census Bureau is not explicit about which household member should complete the questionnaire, but it seems reasonable to assume that children wouldn’t usually be completing it. You can find past questionnaire and instructions here: Sample ACS & PRCS Forms and Instructions

Each decennial census used its own procedure for interviewing households. IPUMS has compiled the questionnaire forms and enumerator instructions for each census here.