Yes...provided that is is in the same booking class that you booked in the airline will give you a travel credit to apply to the next ticket purchased.
Well odds are your ticket in not refundable, but if it is then of course do that.
Otherwise you can do it, because they will charge you a 100 change fee to do that. So you will bascially be right back where you started.
doubt it, but call them, maybe you can cancel that ticket without penalty and apply the it to a new ticket with a credit.
Refund the ticket. They will charge a minimum charge. Issue a new ticket. Better consult with an agent.