1) the name of the checkbox will create issues:
name="venueCheck[<?php echo $row_getVenues['venue_id']; ?>]_<?php echo $RepeatSelectionCounter_1; ?>"
should be:
name="venueCheck_<?php echo $RepeatSelectionCounter_1; ?>"
2) In step three, use the checkbox form element instead of the wada repeat id venue id hidden form element.