Vocalise Romance in C Minor for Voice and Piano

Hello everyone,

I composed this inspired by a composition practice exercise for writing some neotonal music (Bartok, Stravinsky, etc):
    Step 1. Write a diatonic melody in a mode missing one note.
    Step 2. Use a different mode or scale for the harmony.

My melody is in C Ionian without F, and the harmony is C ascending melodic minor (C major with Eb, though I ended up using E here and there too).
I later added a B section with the melody focusing on the unused note F.
The form is ABA'BA.
A' is exactly same melody and accompaniment type but with different harmonies, specially in the first chord, that is Major instead of minor. 

Some of my concerns are:

• Does the piece and structure work overall? There is lots of repetition but I feel that having the harmony of A' changed helps a lot on the overall flow and making the A and B repetition feel anew.  Also, I changed melody on last measure of each A which also seems to help.
• Does the harmony work in general? (There might be some weird spots, specially in section B).
• Does it work well as a vocal piece or another instrument would be better (specially since there are no lyrics)?
• Technically it is in C Minor (it starts and ends in it) but since it uses mostly natural A and natural B throughout, and natural E on the melody, I used the Cmaj key signature. Is that okay or I should change it to using three flats like in natural C minor? 
• I am not sure how to notate the piano sections that consist of ascending chordal accompaniment (with the pedal, although it is not marked). Is there any obvious mistake in the notation?)

Thanks for listening and any feedback is welcome!

PD: I found out that the first 4 notes and main motive of the piece (and the mood, because of the vocal singer) is similar to Jerry Goldsmith's theme to 'The Illustrated Man'. I never heard it before so it was a pure coincidence. I think the harmonization of those 4 notes is different, though. 

I find the music in the tradition of  Ennio Morricone and Nino
Rota .... their Italian movie scores ... a bit of Film Noire here ... hauntingly beautiful music.

Mark