Your first example, only matches a url that is 'fbconnect/register/create'. You could do this much more easily via:
if ('fbconnect/register/create' == current_path()) {
For the second, you'll want to do that via a form alter hook specific to the search block form in a custom module. Assuming the form id is search_block
it'd be:
function mymodule_form_search_block_alter(&$form, &$form_state, $form_id) {
drupal_add_js(drupal_get_path('theme', 'mytheme') . '/js/jquery.placeholder.js', 'file');
}