4. Swing of a node. What is the possible range of the voltage change in a node, that is Vmax-Vmin=Vswing. Rail-to-rail means that you have the maximum possible swing, that is, you are able to achieve swing from ground (0V) to power supply (e.g. 3.3V). Rail-to-rail swing is often desirable on the output and input of the opamp. The simple class A architecture here: **broken link removed** is able to achieve (almost) rail-to-rail output swing, but the input voltage swing is not rail-to-rail. "Almost" because output NMOS may not allow to go as low as in case of AB class.
5. **broken link removed**