[Al_The_Man]

To answer the second question, a buffer is a device to raise the current capability of a SS device or raise/change the voltage level that it works at, It often consists of an open collector output which allows flexibility in output device driving.
In the case of a buffered input, if generally does a similar function, that it conditions the signal you are inputing to conform to the type of technology that the circuit is operating at, i.e. TTL, CMOS etc.
Al.