This is a question about key signature and notation.

Q1) What is the definition of key?

I like to use the harmonic minor scale, especially for faking spanish guitar and metal.

If I write a song that uses the notes of the E minor harmonic scale exclusively, without falling back into an E natural minor or some other related diatonic scale:

Q2) Can the notes that I am using be said to be "natural" to the E h.m. scale?

Q3) Can the song be said to be written in the key of E h.m. ?

Q4) Can the key signature relfect the fact that the only notes in the song are those belonging to the key of E h.m. ?

Q4) If the signature can't indicate minor harmonic tonality, what are the conventions for marking the key signature and notating accidentals?

Answers should be in MLA format, with a works cited sheet included