The Instance will soon be here and I wanna make sure we're all on the same page before they hit us.
This is how I expect us all to approach it…

Finish 'into the dark' attunement quest as soon as.

Abilities - there should be no abilities that you're lacking if something is useful for you desired class, get it.
Abilities on Hotbar - Everyone should have 1) A tier 3 Cure and/or Regen. 2) Raise. 3)Barbs.
There may be times if a mage dies and someone needs to cover healing and raise and the other mages are just not going to have time.
Bring food.

Various weapons, expect different mobs to be have different damage mitigation. Some perhaps weak to blunt some piercing.
Bring a few weapons if you can to test or even better kit for a class change within the instance if needed.
The same with magic, some mobs might have different resistances, test all magic and pay attention to combat log to notice any differences.

Threat - 1.18 will have a basic visualisation of how much threat/hate everyone has.
As I would expect, tanks red, offtanks and melee yellow, ranged and mages green. It should be easier to control aggro.

Other things… this instance has been quoted as 'difficult' by the devs on the forums.
Expect anything, we know that various routes can be chosen to decide the outcome of loot.
Bosses- expect AoE conal/radial, hate reset, adds etc.

Take screenshots of everything, how mobs patrol, any choices or other options to take, combat logs everything.

I almost forgot.. remember Incap and regimes they'll probably play a part
http://lodestone.finalfantasyxiv.com/pl/guide/battle02.html

Oh and DKP. don't worry about that for now, raid attendance will be logged but no system implementation until we know enough about the instance.