Do this instead:
a.wp-show-posts-read-more:hover,
a.wp-show-posts-read-more:focus {
border: 1px solid #222;
background-color: #b72e09;
color: #fff;
}
As for the loading text, do this:
add_filter( 'wpsp_ajax_loading', function() {
return 'Your text here';
} );
