Why does this band have special operating characteristics and what do they mean.
The ARRL has a good FAQ page about the 60 meter band. The special rules in the United States for the 60 meter band aren't due to any technical limitations. Instead, they're a compromise to allow amateur use of the band without interfering with government use. The primary users of the band are government agencies, and they were using it long before amateurs were granted access. As secondary users, amateurs are required to stop transmitting when asked to do so by another user, or if they detect non-amateur transmissions on the channel. The channels were selected because they're lightly used frequencies that are least likely to cause interference with the primary users.