#1-
A company that doesn't routinely get electrical work inspected (such as a manufacturing or other industrial or municipal facility) CAN "instantly" adopt the latest NEC. These type of places usually have a maintenance manager or other type of group leader that can simply insist that all work conform to the latest edition. I think some of the lag associated with municipality adoption is due to red-tape. They probably SHOULD do so because the assumption is that each new NEC is "new and improved". So, why wait if you don't have reason to?
#2--
As far as the role of the NEC in areas with local codes. I always thought that the NEC was as used as a foundation for these local codes, and therefore, their codes include the NEC, along with requirements that are above and beyond the "minimum" put forth by it.
