how to change the gridview row color

For changing row's background color and Font color in a datagridview use following lines of code:

int n = 0;
   foreach (DataGridViewRow rw in dataGridView1.Rows)
   {
   // First put a check to avoid newRow error 
   if (rw.Index != dataGridView1.NewRowIndex) // To avoid newRow error 
   {                                          
      // You can replace your condition with the following line
      if (String.IsNullOrEmpty(rw.Cells[0].Value.ToString()) != true)  
      { 
           DataGridViewRow bandrow = dataGridView1.Rows[n];
           DataGridViewBand CatBand = bandrow;
           DataGridViewCellStyle Rwstyle = new DataGridViewCellStyle();
           Rwstyle.BackColor = Color.Lavender;
           Rwstyle.ForeColor = Color.MediumBlue; 
           CatBand.DefaultCellStyle = Rwstyle;
      }
   }
n++;
}

For rest of the points please explain your problem little more.