different noteheads / changing instrument / vertical rest-position

[Peter Maier]

Hi!

I want to make a drumset score. 

1. For this I need different noteheads for cymbal (cross) and the rest of
   the drumset (default). I have tested the example where different
   noteheads should be created. but I couldn't compile this example. (the
   lilypond-compiler didn't recognize \set and \cross and some more
   things) i have modified this example until the compiler could work with
   it. but now all noteheads look like the default one. 

2. I want to create a midi output-file with drumset instruments. how can i
   change from piano to drums?

3. I have 2 voices in the score. if there are in the upper voice one
   quarter note and three crotchet rests (r4 c r r) and in the lower voice
   is a semibreve (r1) then the last two rests are printed in the middle
   of the staff.
   but i want to print all rests of a voice in the same height.
   how can i tell the compiler that all rests of the upper voice should be 
   printed on the upper half of the score and the rests from the lower
   voice should be printed on the lower half?

Thank you for your help!

ciao peter.