In certain flood prone areas it is already requird by code. Has been for a number of years in some places. It is js ut common sense if you are prone to flooding either on the coast or the banks of a river. Houses in Florida and the New Jersey shore have been rasied on pilings for the same reason.
Every building? Yes, but for many it makes a lot of sense. In some areas there are even basement apartments that are about six feet below grade. Makes for some interesting things in the bathtub when plumbing problems happen.
Las Vegas is using elevated walkways to avoid traffic. It can easily be used in other areas too. Well, maybe not always easily, but it is not a bad idea.
Maybe. In New York it is common to leave a car parked or "stored" for weeks at a time. Parking, storeage, just variations on termonology.