Creating a hex map

Hello! I'm trying to do a hex map for my game, so I have a couple of questions.

The first one: should I draw every hex as a separate game object or it will be better to combine them into one mesh?.. Or it will be better to divide a map on a few chunks? I'm planing that the map will be about a 1k x 1k hexes.

How could i make a soft transition between two hexes? Like it was done in the "Endless Legend": Or in the Civilization 5: