How can I change the URL to which the plugin redirects once a user unsubscribes?

Hook
wcal_unsubscribe_redirect

/**
* Add this code snippet in the "functions.php" file of your currently active theme.
*/
function change_redirect( $url ) {
	$url = get_permalink( wc_get_page_id( 'shop' ) ); // Redirect to the Shop page.
	return $url;
}
add_filter( 'wcal_unsubscribe_redirect', 'change_redirect', 10, 1 );

How can I modify the number of entries displayed on the Abandoned Orders page?

Hook
wcal_abandoned_orders_per_page_count

/**
* Add this code snippet in the "functions.php" file of your currently active theme.
*/
function modify_count( $entry_count ) {
       $entry_count = 50;
       return $entry_count;
}
add_filter( 'wcal_abandoned_orders_per_page_count', 'modify_count', 10, 1 );