The one thing I couldn't figure out this weekend if it was possible to do person to person trades like you can in Guild Wars 1. Is that possible or will it only be limited to the Auction house or Guild Storage?
The only way to do person to person trading is to use the mailing system. This is a deliberate decision to encourage the use of the cross-server Trading Post (auction house), to discourage people standing around in common areas shouting "Want to Buy/Sell/Trade", and also to discourage the likelihood of players getting scammed through those player trades.
Face-to-face player trading is not in game and will not be in the game at launch. In a fansite interview with Colin Johanson, the Lead Content Designer, he stated the following, emphasis mine:
How has player to player trade been improved?
Colin told us about the marketplace. In the marketplace the player has the ability to not only buy and sell items like a traditional auction house, but also place “Wanted” ads in there stating which item they’d like and for what price. In this system a seller can activate the ad and the transaction will automatically occur with both items being removed from the two players inventories.
Similarly, personal player to player trade can be done through the in-game mail system (see above question for details). Unfortunately, there is no face-to-face trade (ala GW1) in the game at launch.
As of release, there is no COD for mailing, which means it is still possible to be scammed through mail trading.