<script type="text/javascript">
$(function(){
  $(":button[name=btn1]").click(function(){
    var $select = $('<select>');
    var $option1 = $('<option>');
    var $option2 = $('<option>');
    $option1.text("オプション１");
    $select.append($option1);
    $option2.text("オプション２");
    $option2.attr("selected","true");
    $select.append($option2);
    $("#select").append($select);
    
    $(this).attr("disabled","false");
});
</script>

<script type="text/javascript">
$(function(){
  $(":button[name=btn2]").click(function(){
    $("#sample").val(2);
  });
});
</script>