Reissue ticket?
 

Suppose there is a big price drop on a ticket you bought. Can you "reissue" the ticket for the exact same itinerary, e.g. "refare" it? If so, can this be done online? Will you get a refund for the fare difference (minus some fee) or does this not work at all?

Many fares now have a restriction that new ticket needs to be of equal or higher value. Have you purchased via a travel agency? They would be able to check it for you. Otherwise you need to call TK :D

Well, I decided to just buy a ticket and not bother checking anymore. Only gives me high blood pressure :D
Will be my first time flying TK :)

No, the airlines will not accept that. You would have to cancel and rebook.

That is the right decision/way to go.

I'm sure you will be satisfied with TK - in many ways it is a great airline