Am I able to use an external HDD to install games from eshop on? I'm thinking of getting W101 as my free game and creating a partition on my HDD for it but im not sure if this is possible

Been a long time since i played this game. I got 100% in the game before any of the dlc was released. So my questions are:

What's happened/happening with the ending? It was that bullcrap "tbc" that I'm still vexed about. Has there been any dlc that ended the story? Or will it be a XIII-3?

And on the note of dlc, have they been any good? I want to get back into the game but is it even worth buying the dlc or should I just hang around until they eventually release a new FF?