Mayfair GamesCatan: Seafarers Expansion 4th Edition

Is there any way to know if this will match my current edition base game?

I already have the base game(3-4 players), does this expansion allow for 5-6 players?

We can't seem to setup the board. It seems as though boarders are missing. How many boarders are there? Help would be appreciated.

The description states that this is the 4th edition, yet the pictures have tiles that look like an earlier edition. Are the tile pics inaccurate?