2. Pin 7 and 14 of 2.IC are power pins, which are power ground and Vdd respectively. These two pins may or may not be connected to any of the six inverters.
3. Usually, these two pins can't be found in the component library.
4. The output amplitude of this circuit cannot be linearly proportional to the input amplitude, and the height of the output square wave is about Vdd (if the DC component is filtered out, the output amplitude is about Vdd/2).