What to prepare for Shadowbringers?

[Edax]

Honestly, I would ask you to mentally prepare for early access because it won't be pleasant. Some people may face upwards to 45mins ~ 2hrs trying to login to their world. Some may not get to access/enter mor dhona if the devs don't open 3 instance channels for that area. We may get DDOS because people don't like others having fun.(Very high chance of occurring) Duty finder server will maybe crash/lag in the first few hours.

For gears and weapons i wouldn't worry as the first few MSQ will reward you with HQ gears and weapons.
New jobs will award players with job gear and weapon box when you accept them.

I am prepared for this due to my experience with SWTOR and WoW, however it's been many years since I played them so I cannot really remember how long it took for the servers to stabilize. Does it take about a week to stabilize?

Probably a good idea to cap all your tomes and seals where you can. They will convert to the new currency.

Will it take reaching level 80 to be able to spend the new currency on gear?