Regarding question 2) I see the preferred method is:
<?php
                    if (ValidatedField('ratesandavailabilityx_878', 'ratesandavailabilityx_878')) {
                        if ((strpos(("," . ValidatedField("ratesandavailabilityx_878", "ratesandavailabilityx_878") . ","), "," . "" . ",") !== false || "" == "")) {
                            if (!(false)) {
                                ?>

