All is in the title! ^^

I've the same question : i bought this game 1 mouth ago the official release but i don't have the pre-order goodies, just basic skin/weapons

Just to be clear, the Pre-Order Bonus only consists out of three pieces.
A skin for you mount (which should always be actice as it can not be equipped), a shield and a scythe.
Both were in my inventory right from the start.

If you use Galaxy there should be a checkbox for the pre-order items in the settings menu for the game in the Galaxy client.
If you play it without Galaxy then you simply should install the preorder file which can be found in the Backup & Goodies menu.

I hope that this helped you guys