Welcome back!

1. To my knowledge you have to demolish your private chamber first or it won't let you leave your FC. If this isn't the case and you can leave your FC without demolishing your private chambers, then all your furniture should be with the caretaker/enthusiast (don't remember) within the housing zone.
2. You can find the instructions for using your early access code for your platform and method of order here. If you ordered a digital copy of the game my guess would be that you would receive a code for the full game on launch day. However if you're talking about downloading Heavensward then you should be able to download Heavensward sometime on the 18th (my guess considering that's maintenance day) as long as you've got your account registered for early-access.

You will have to complete the Main Scenario Quests up to and through 2.55 (the last quest is "Before the Dawn") to access Ishgard and therefore pretty much all the new content. ilvl 90 is the highest ilvl required to complete the Main Scenario so you're set there . You are currently at/just did Keeper of the Lake so you should have 2 more trials to do within the Main Scenario, the rest is just quests. At this point, don't bother grinding for new gear it will get replaced in the expansion and unless you have a burning desire to finish the relic weapon/want it for glamour, I don't think you should bother with it.