You can apply for a new US passport or passport renewal and a US passport card at the same time. This is a convenient option for frequent travelers to have both a valid passport for air travel and a passport card for travel to these destinations by land or sea.
As for when you should use a Seal... use Master Seals on non-promoted classes at level 10 to upgrade them, and Second Seals on non-promoted classes at 10 to switch them over to another class tree (mostly worthless, though switching characters that have access to Mercenary, such as the Avatar, over to it ASAP is generally a good idea), or to switch a promoted class into another promoted class at level 15.
You need to get a [Flight Master's License] , which allows you to ride flying mounts in Eastern Kingdoms and Kalimdor. It requires the Cataclysm expansion be activated on your account to use. It also requires level 60, and 250 gold (reduced to 200 gold with exalted faction reputation).