The $100 standby fee is scheduled to take effect 1/1/03. There's no charge on UA for standby from now to 12/31/02 if permitted by the fare basis of the ticket you purchased.

Applying your non-refundable to a refundable should not work if they execute the rules correctly. The non-refundable part remains non-refundable, plus tickets with multi-fare basis codes are supposed to take on the most restrictive rules of the various codes, meaning your new ticket might also expire if not changed before the date of travel.