Fall, leaves, fall

This is a song based off of Emily Brontë's fall, leaves, fall

I have one main question about composing in general. In my song I re-use parts of the poem later, to help the listener process what the phrases mean. Is this 'allowed'? (answer with either opinion or facts)

If you could give me primary feedback on the effect I made, and whether or not you feel it properly displays the poem. That would mostly appreciated.

Also, what is voice leading? And am I doing it right?

1.  Everything is allowed, you just have to be sure you cite your sources properly.  In this case, that means it's nice to print the poem in its original form on the first or last page of the score, to aid a director who wants to print the text in a concert program, and to help the singers see what you are doing to emphasize text, compared to what the original writer did.  It may influence how they choose to handle a dynamic to carry that emphasis into their musical performance.  All information is good information.  Repeating phrases is particularly common when counterpoint might obscure them for the audience, so you've made a good decision to do it here.  

2.  Voice leading is the way that the chord structure and each note within the chord flows logically into the next, so that the next note "makes sense" for each part.  You do it when you write for any group of instruments, but it's particularly important for singers, since so few people have perfect pitch.  A violinist or a piano player can put their finger in the right spot and get the correct next note every time (in tune is a separate question), but if you are currently in the key of C major, and singing a G natural, and your next note a Bb for some reason, how do you pluck that out of thin air and sing the right note, without taking two seconds to think about it (and coming in late as a result)?  Good voice leading means that the next note is somewhat intuitive.  Choir directors do warm-up exercises where they have everyone sing a given note and then point at different voices to ascend or descend by step, or by thirds to change the chord, and at some point, having established the key in this way, they say, "now everyone resolve, ready?  Now."  And everyone changes note to resolve the chord, without thinking about it too hard, because at that point the steps you have taken so far have set up the expectation of where "resolved" is, and there is only one right answer.  The human heart just feels it intuitively.  It's what we respond to when we listen to music.  You can google "rules of voice leading."  You can also set the playback feature in your composition program to mute one voice part, and try singing it while the other parts play back.  Anywhere you catch yourself singing a wrong note or just feeling particularly hesitant, your voice leading may be to blame.  (You wrote the thing, if you can't sing it correctly on the first try, god help the poor singers in a choir that tries it).  This looks pretty good.  No part crossings.  (Yes, you can have lines cross each other, when that is what makes most intuitive sense for the lines because of patterns you've already established, but you don't want to do it too often).  Lots of stepwise motion.  (It's pretty easy for someone to find their next note when it just moves up or down the scale).  And when you do have someone sing a skip, it's by an interval that's easy to find:  perfect fifths.  

3.  Yes, this is a great effort at setting the text.  I can hear the leaves falling and a sense of melancholy at autumn from the beginning piano intro.  Nice job!