Guild Wars 2

Based on the FAQ about the pre-purchase of HoT:
Additional exclusive pre-purchase offers
We’re offering some special deals to show our appreciation for loyal players.
Free character slot
If you registered your core Guild Wars 2 game before January 23, 2015 and register a pre-purchase serial code for Heart of Thorns any time before the expansion is released, you’ll receive a free character slot! Once you apply a pre-purchase serial code, you’ll be eligible for the slot regardless of where you bought the core game.
If the serial code you used to register the core game came from a retail vendor (rather than buy.guildwars2.com or in-game) and was applied to your account between January 23, 2015 and June 16, 2015, you’ll also be eligible for a free character slot if you apply a Heart of Thorns pre-purchase serial code before the expansion release.
All accounts that become eligible by July 9 will have their free character slot applied by July 10. Eligible accounts that are upgraded with a pre-purchase serial code after July 10 will receive their slots on a weekly basis after that.

I have a question about this extra character slot…. is this in addition to the character slot that you get as a part of the package of buying it? or is it just one slot that you get for free?

If you pre-purchase the Deluxe or Ultimate Edition, you would be eligible for 2 character slots. If you pre-purchase the Standard Edition, you would be eligible for 1 character slot.

It’s in addition, so if you buy deluxe or ultimate, you’d get two character slots. You’ll get the slot that comes with the package faster, though, as the free veteran slots are distributed on a weekly basis I believe.

awesome, thanks Inculpatus and Scratcher