You migrate the apps but if you migrate your data it will probably create a new account, so I'd advise copying the data by just dragging into ~/Documents. Firewire is your best bet, unless you have Thunderbolt.
As far as selling, you need to erase the drive and install from the original install disk that Mac shipped with. This is required by license agreement. Also right now, it is tied to your Apple ID. Without your password the new owner won't be able to upgrade or purchase anything from the app store. With it he'll be able to run up quite a bill for you. You also risk leaving behind easily recoverable pesonal files, if you don't do a full security erase.