Ah, you found the creation node... haha, yes quite confusing. In addition to the shape and transform nodes of an object, there is a node that contains all the info on how it was created. That is your "polyCylinder". In your channel box you can use this node to change divisions, radius, etc. If you delete history, or have construction history turned off, that node will not appear, or it will be disconnected. For most things you can safely ignore the name of this node.

pCylinder1Shape: No, because the number always comes last. I think that's so maya can auto rename easier. If you duplicate, you will notice it becomes pCylinder2 and pCylinderShape2. Also, the reason the creation node is called poly... yeah, confusing, but it is to distinguish it from the transform and shape nodes I think.