unwanted P tags in shortcode, delay wpautop not working

The simple solution is to not give wpautop anything to chew on.

function contact_us() {
    $str = "<p>Here's the low down on what to do</p>";
    $str .= '<link rel="stylesheet" type="text/css" href="http://code.jquery.com/ui/1.10.0/themes/base/jquery-ui.css"/>';
    $str .= '<link rel="stylesheet" href="http://studiocloud.com/css/validationEngine.jquery.css" type="text/css"/>';
    // etc
    $return $str;
}

Your generated code won’t be formatted, but there is no reason it should be. We are long past the days of static HTML, at least I am ( “Thank you” to the Lords of Kobol ), where such formatting mattered. Now, all that formatted is just unnecessary characters that have to travel down the wire.