WITH BELLS ON... meaning happy and delighted to attend which goes back to the days before the automobile, when it was the custom to deck out the horse with fancy harnesses, that drew the carriage for special occasions. That, of course, was the harness 'with bells on.'
Carrying the Bride over the threshold of the new marital home symbolises medieval 'kidnapping' when they enter the marital home for the first time. If the bride entered the home with her left foot first, she would be visited by bad fortune. In order to avoid this disaster, the groom lifts her into the home.