simple choral example: warnings/clashes and no midi

[ivan . k . kuznetsov]

I am still relatively new to lilypond.
I have a simple four voice choral attached.


(1)
This example produces numerous warnings about
clashing notes which look like:

    choral-beethoven-moonlight-01-simple.ly:16:62: warning: ignoring too many 
clashing note columns
        e'2  e'2   e'2   fs'2    fs'2  e'2   ds'!2   ds'    cs'

Why is this happening?

(2)
Also, this example fails to produce a midi file.
Can someone explain what I am doing wrong?


(3)
As far as the structure of my file:

  \new PianoStaff
  <<
     \new Staff = "up"
     {
       <<
       \new Voice = "up" { }
       \new Voice = "up" { }
       >>
     }
     \new Staff = "down"
     {
       <<
       \new Voice { }
       \new Voice { }
       >>
     }
  >>
  }

Is this considered an example of "best practice", or how
might others structure a four voice choral.


(4)
Finally, at the beginning of the four measure in
the soprano and alto, the d# and c# collide.
I would have thought lilypond would have taken care
of this.  What do I need to do to fix this?



Thank you very much for your time and patience.



\version "2.16.0"
\include "english.ly"

\score {

  \new PianoStaff
  <<
     \new Staff = "up"
     {
       \clef "treble"
       \time 4/4
       \key cs \minor
       <<
       \new Voice = "up"
       {
          e'2  e'2   e'2   fs'2    fs'2  e'2   ds'!2   ds'    cs'
       }
       \new Voice = "up"
       {
          cs'2  cs'2  cs'2 d'2      bs2  cs'2  cs'2   bs2      gs2
       }
       >>
     }
     \new Staff = "down"
     {
       \clef "bass"
       \time 4/4
       \key cs \minor

       <<
       \new Voice
       {
          \stemUp
          gs2 gs2 a2 a2   gs2 gs2 gs2 fs2   e2
       }
       \new Voice
       {
          cs2 b,2 a,2 fs,2     gs,2  gs,2  gs,2  gs,2   cs2
       }
       >>
     }

  >>
  }

  \layout {

    \context {
       \Score
       \override SpacingSpanner
       #'base-shortest-duration = #(ly:make-moment 1 8)
    }
  }
  \midi {
     \context {
       \Score
       tempoWholesPerMinute = #(ly:make-moment 72 4)
     }
  }