My next problem is removing the "* Required" text next to the telephone input field...
Figured it out...

Around line 803 in admin/customers.php, change this:

Code:
echo zen_draw_input_field('customers_telephone', $cInfo->customers_telephone, zen_set_field_length(TABLE_CUSTOMERS, 'customers_telephone', 15), true);
to this:

Code:
echo zen_draw_input_field('customers_telephone', $cInfo->customers_telephone, zen_set_field_length(TABLE_CUSTOMERS, 'customers_telephone', 15), false);