netbie on "Tags and Categories Hack help"

I am using this code for display the Tags inside one category

<?php
//get category name
$catname = get_category(get_query_var('cat'))->name;
//get all tags in this category
query_posts("category_name=$catname");
if (have_posts()) : while (have_posts()) : the_post();
$posttags = get_the_tags();
if ($posttags) {
foreach($posttags as $tag) {
//Get Tag ID
$all_tags_arr[] = $tag -> term_id;
}
}
endwhile; endif;
//remove duplicates
$tags_arr = array_unique($all_tags_arr);
?>

I have 2 questions:

1) How can I display these tags as DROPDOWN instead of Tags Clouds ?

2) How can I do the same but inverse: I mean display the Categories inside One tag, as DROPDOWN.

Thanks in advance for your help.