I teach citizenship classes to native Spanish speakers, and often am asked to fill out N-400s for them. I always tell them I am not a lawyer and cannot give legal advice. But I do give them information from the instructions, if needed. I read the questions to them (sometimes translated into Spanish) and write the answers they give me. Then I sign the last page of the form, as the person who helped prepare the application, giving my personal contact information.
Not unless you are actually providing "legal advice." If you are simply serving as a scribe for the person and helping them fill out the form in English from Spanish and translating it is fine.
The information provided in this answer does not create an attorney-client relationship and is not considered to be legal advice.
I do not believe your actions constitute the unauthorized practice of law. You are simply functioning in the capacity of a translator and not providing legal advice or an opinion.
No, if you do not provide legal advice.
The information contained in this answer is provided for informational purposes only, and should not be construed as legal advice on any subject matter,not should it be viewed as establishing an attorney client relationship of any kind.