winock2014 on "widget with related post on a category and there tags"

i need a related post widget in my wp website, a widget with related posts from a categorie and the result of five posts with the permalink. After the title of the widget and befor the results i need a dropdown menu with the choice of the tags from the choosen categorie thats already showing 5 posts.

after clicking one of the tags the results should come in the same widget.

The code i have:

<?php query_posts('category_name=impressions&showposts=5'); ?>
<?php while (have_posts()) : the_post(); ?>
<li><a href="<?php the_permalink(); ?>"><?php the_title(); ?></a></li>
<?php endwhile; ?>

I do not need a ready to use widget because i use the php-code-widget, also there is no possibility for in example a tag cload, the point is that i use in my footer four times the same widget for different categories, each with there own tags...

I have no knowledge about PHP, i hope somebode can help me on this?

Patrick