Nightfall Pre-Order Extra Slot Question

I was wondering can you add 2 extra preorder Charactures slots?

Lets say my friend preorderd NF but didnt need the extra slot... can i use it too?

Becase then... extra slots are only 5 bucks

Im wondering if Nightfall will come with an extra character slot in the standard retail edition?

Are we required to buy the pre-order to get the Extra Slot that the pre-order box advertises? Or is this pre-order slot in addition to an extra retail package slot?

Pretty sure this is how the character slots work for Nightfall.

If you add NF (Standard or CE) To your prophecies/factions account you get an extra 2 character slots. If you add a pre-release NF key to your account, you get an extra slot when NF is released.
If you add 2 pre release keys to your account, I think you get an extra 2.

One pre-release key per account.

I found my answer in the FAQ:

Q: Do we get a free character slot via the Pre-order Pack? And how is it affected by Account Merging?

A: Yes, if you add a Pre-order/Pre release Key to your account you will get 1 free character slot once you add a full Nightfall Retail key to your account.

To prevent misunderstanding it's been confirmed again by ANet and NCsoft that the character slot that comes with the Prerelease Bonus Pack really is in addition to the ones that come with the game, giving you 3 slots for a merged account or 5 slots for a stand-alone Nightfall account.

You can only add one bonus pack key per account.