What happens when you put all 9 pieces of each map together? Is one complete map any better than another one? Can they be used more than once or would I have to put together another set to do the same thing?

Thanks in advance for answering.

I think this page can help you. But I do believe you can only use each map one time without recollecting all the pieces; it disappears after you use it.

The map to the uncharted land gives you access to the unknown island. The other ones you get stuff and an achievement.