location of rests and bar alignment between staffs

[Brian Kidd]

Hello,

I'm new to lilypond and would like to create notation for an ensemble  
of hand drums. Currently, I'm having trouble with two specific layout  
issues and I wasn't able to find exactly what I needed in searching  
the archives. The first is how to position a rest relative to a  
single line so that the rest symbol is centered on the single line.  
Is there a way to define the default rest position relative to the  
line? The second is how to adjust the horizontal spacing of each bar  
so that they are aligned between each staff. I've had a lot of  
trouble with this issue and tried tweaking a number of parameters  
including proportionalNotationDuration and the SpacingSpanner, which  
hasn't produced the desired results.

I've included the syntax and the output it produces.

Thanks,
-Brian

#(define mydrums '(
    (bassdrum           default #f      -1)
    (acousticbassdrum   default #f      1)
    (hihat              cross   #f      -1)
    (closedhihat        cross   #f      1)
    (snare              harmonic    #f  -1)
    (acousticsnare      harmonic    #f  1)
    )
)

drumOne = \drummode {
    \override Beam  #'positions = #'(3 . 3)
    sn4._\markup{!} sn8[r8 sna8]^\markup {signal} r8[r8 sn8] r8[r8  
sna8] sn4. hh8[r8 hhc8] hh4. r4.
    \bar "|:" bd4. hh8[r8 hhc8] bd8[r8 sna8] sn4. bd4. hh4. bd8[r8  
sna8] sn4. \bar ":|"
}

drumTwo = \drummode {
    \override Beam  #'positions = #'(3 . 3)
    s1. s1. \bar "|:" hh4._\markup{*palm slap} sn8[r8 sn8] r2. sn4. _ 
\markup{!} sn4. _\markup{!} hh8[r8 hhc8] r4. \bar ":|"
}

\new DrumStaff <<
    \override DrumStaff.StaffSymbol #'line-count = #1
    \override DrumStaff.BarLine #'bar-size = #4
    \time 12/8
    \set DrumStaff.drumStyleTable = #(alist->hash-table mydrums)
    \new DrumVoice { \voiceOne \set Staff.instrumentName = "Drum 1"  
\drumOne }
>>

\new DrumStaff <<
    \override DrumStaff.StaffSymbol #'line-count = #1
    \override DrumStaff.BarLine #'bar-size = #4
    \time 12/8
    \set DrumStaff.drumStyleTable = #(alist->hash-table mydrums)
    \new DrumVoice { \voiceOne \set Staff.instrumentName = "Drum 2"  
\drumTwo }
>>