How do i combine POSTS and PAGES in one listing?

It depends on exactly where you want to do this and how you want them displayed, but you can start by creating a custom query that returns both posts and pages:

$args = array(
    'post_type' => array(
        'post',
        'page'
    )
);

$my_query = new WP_Query( $args );

You can find other parameters here:

http://codex.wordpress.org/Class_Reference/WP_Query#Parameters

Then you would just loop through the returned posts/pages and display them however you want.

query_posts is for altering the main loop. What are you wanting to accomplish?

For secondary loops using get_posts or manually creating new WP_Query objects like my example above is generally the way to go.

Template Tags/get posts
Class Reference/WP Query

Without knowing specifically what you’re looking to do (including your current queries or what posts/pages you’re looking to query for, the order of their display, what exactly you mean by a slider, etc.) it’s difficult to comment on anything else.