No, derailleurs are not indexed the shifters are. The derailleur may or may not be compatible with an indexed shift lever. I don't know what if any Campy components are indexed before Ergo levers. A high quality, reasonably modern friction system will shift so much better than what you had you might not miss the indexing. Both the Athena and Chorus will be a huge upgrade.

Parallelogram is a shape, a pantograph is a mechanism for translating motion. Pantographs tend to use linkages in the form of a parallelogram.