Here you can see three functions which all playback the sound samples, just in different ways...

playback(); plays back a sample forwards.

playback_r(); plays the sample backwards.

playback_s(); plays the sample forward but at a reduced speed.

void playback(prog_uchar *sample_ptr, unsigned int length) {
        unsigned char bite; int col; col = 0; int i;
        for(i=0;i<length;i++){
          bite = pgm_read_byte_near(sample_ptr + i);
          unsigned char mask = 1; unsigned char copy = bite; int z;
          for (z=0;z<8;z++) {
            digitalWrite(SPK_PIN, copy & mask);
            copy = copy >> 1;
            delayMicroseconds(25);
          }
        }
}
void playback_r(prog_uchar *sample_ptr, unsigned int length) {
        unsigned char bite; int col; col = 0; int i;
        for(i=0;i<length;i++){
          bite = pgm_read_byte_near(sample_ptr + length - i);
          unsigned char mask = 1; unsigned char copy = bite; int z;
          for (z=0;z<8;z++) {
            digitalWrite(SPK_PIN, copy & mask);
            copy = copy >> 1;
            delayMicroseconds(25);
          }
        }
}
void playback_s(prog_uchar *sample_ptr, unsigned int length,unsigned int speed) {
        unsigned char bite; int col; col = 0; int i;
        for(i=0;i<length;i++){
          bite = pgm_read_byte_near(sample_ptr + length - i);
          unsigned char mask = 1; unsigned char copy = bite; int z;
          for (z=0;z<8;z++) {
            digitalWrite(SPK_PIN, copy & mask);
            copy = copy >> 1;
            delayMicroseconds(25*speed);
          }
        }
}

By mixing up and fooling around with chopping up the samples, I was able to create some interesting variations with just the 4 basic samples that I started with.

int z;
for (z = 0; z < 4; z++){
  playback(onebitraw_1, BC_BYTE_COUNT_1 /4);
  playback(onebitraw_2 + (BC_BYTE_COUNT_1 /4), BC_BYTE_COUNT_1 /4);
  playback_r(onebitraw_3 + (BC_BYTE_COUNT_1 /2), BC_BYTE_COUNT_1 /4);  
  playback(onebitraw_2 + ((BC_BYTE_COUNT_1 /4) + (BC_BYTE_COUNT_1 /2)) , BC_BYTE_COUNT_1 /4);
}

That code block allowed me to cut up the samples, maintain quantization and make the pattern far more interesting.