1. Porting to it has been brought up occasionally and Square Enix wants to do it, but they have a lot of other priorities and there have been issues with Microsoft wanting exclusive servers so that you can't interact with people who play the PC or Playstation versions. If those restrictions are lifted, Square Enix will probably do it when they are not overwhelmed with other tasks such as an expansion release, FF16 or a global pandemic.

Since these things take time, it probably isn't worth expecting it any time soon.

2. The PS5 or PC option is your best hope unless you are prepared to wait a few years to see if there is a change on the status of an Xbox version.

3. Marriage is free on the mog station (but you still have to add it to a cart). There are paid packages that allow for more customization and a mount though.

You can get a house but the housing market is very competitive. There is a housing crisis just like in many places in real life and just like in real life, getting one is hard on many servers. There is a lottery system, although you can share a Free Company house and get a small room in one, or an apartment room which is also small. You can enter eachother's rooms.