1. Once you get to level 17 you can undertake Low Level Duty Roulette. This grants a huge bonus to experience. You actually get an even greater reward if you are playing a class that's dubbed "Adventurer in Need", i.e there is a high demand for a Tank or Healer in the queues. Sadly, DPS classes do not get this additional bonus, because the queues are generally saturated by them. There is also the Challenge Log which you can unlock from I'tolwann in Limsa Lominsa Upper Decks (x11,y10). You need to have completed the quest "Call of the Sea" first, through. The Challenge Log grants a weekly list of tasks that give bonus exp, PvP exp, Companion experience and Gil for completing the set tasks. This resets every week.

2. Housing has been implemented. You have to be in a Free Company to have a House though. And they are expensive, so it's probably best to join an FC that already has a House. The demand for plots on some servers are quite high, with some being completely gone so chances of starting another Free Company, and being able to save the prerequisite funds to own a House is quite slim. However, as of patch 2.3 the introduction of Personal Rooms were made. You still need to be part of a Free Company with a House, however if you are at the current maximum rank with your Grand Company (Second Lieutenant), and have 300,000 gil to sink into a Personal Room, you can purchase your own space within your Free Company House. It is an independent, separate instance that you can completely furnish yourself.

The other benefits to having access to a house is Gardening, and Chocobo Raising.

3. Money can be pretty easy to come by in a variety of ways such as the Challenge Log, or even just FATEs, Levequests, or running dungeons. However, I have found the most I have made was from selling Materia. When you wear non-rare equipment you spiritbond with it. Once you have your spiritbond to 100%, you can convert the equipment into a piece of Materia. Sometimes, you may be lucky and get a grade IV Materia. These can sell for 6 figures on the market.

4. There is a variety of content. Main story, side quests, relic weapon quest, Crystal Tower, Binding Coil of Bahamut, Wolve's Den (PvP), Frontline (PvP), Moogle Delivery Service, crafting, Beast Tribe daily quests, Retainer Ventures... there is a plethora of content to keep one entertained.

I hope this helps you.