I just mailed in my voucher for a ticket less than two weeks away rather than going to the airport. They didnt charge me any taxes...is that standard? I thought even for free tickets you have to pay a booking fee and taxes?

Also, can you standby for a later flight on the day of travel (only able to get the 6am flight) or can you switch flight times (not connection city or routing) if inventory opens up before date of travel free of charge?