Welcome back to Eorzea!

A good place to start to get caught up on all the many changes that have occurred since your absence would be to have a look at the patch note listing, as there's been quite a number of major content patches that added a lot to the game (and changed things): ARR and Heavensward Patch Note Log.

As for player housing, the 2.1 patch notes should mention the basics, but at this time, many servers are suffering land shortages (there are only a limited amount of lots available and they've all been bought up), meaning unless another player is willing to relinquish their block and allow you to then purchase it, you will be unable to get a house sadly. SE are meant to be adding more land sometime in the near future though.