CPLD ispmach 4256ze starter pin connention configuration
What you need is the data sheet(s) for the device.  There are usually recommendations on how to make the various connections.
Since your questions are "general," the answers can be provided by anybody that has electronics experience.
For your first question, yes, the gnd pins should all be connected to common ground (better to be safe).
For the second question, each of the VCC pins are for providing a different "hi level" voltage (5v, 12v), rather than the voltage provided to the chip (3.3v, 5v).  If these pins are outputs that won't be used, then leave them unconnected.