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.
If the BM is 3.5 and the FF is to be at 7.0 you go to 7.0. So you need to be 3.5 above the BM. I assume you're saying the finished floor elevation needed is 7 foot. If so then whatever the value of the benchmark is subtract that from 7 to get the value you have to go up. However the value not being out to the thousands I doubt it's a certified benchmark.