Regarding ticket "expiration" dates.
If a never-used ticket is allowed to "expire," it only means that the ticket in question cannot be used, "as-is," past a certain date.
The guest would then need to (in effect) "upgrade" that expired ticket into a brand new ticket.
(The guest would be able to enlist the original value of the "expired" ticket, plus adding the difference price for the new ticket.)
The new ticket can then be used at WDW.
The basic reason for this is to disallow guests from buying a "stack" of (relatively) lower-priced tickets today, with the specific
plan of holding them for use at a future date, after newer tickets have risen in price and/or have revised "ticket rules."
So, if a guest's plans change, the amount paid for tickets is not "lost."
It just means that the guest would need to pay the "up charge" for more current tickets for use during the revised travel dates.
(Not unlike needing to pay the new current resort prices in effect for the revised travel dates.)