Hi Peter, all the plays you mention are lost to the Byzantine manuscript traditions of Greek dramatists. What survives of the plays you mention are only fragments, i.e. quotations in later writers (I don't know about scraps of papyrus). For fragments of Attic comedy, the standard collection is Kassel-Austin, Poetae Comici Graeci
The fragments are given in Greek, and explanations in Latin.
John Maxwell Edmonds did an edition of fragments of Attic comedy, published by Brill, with English translations. Scholars generally don't cite from his edition, but if you can get it, you'll get the translations. If you want to write a scholarly presentation, you should cite the fragments by number from Kassel-Austin.
Ian Christopher Storey has a new book w/ translations of the fragments of Eupolis. Google books doesn't give all the pages, but their search engine will reveal pages where Storey discusses Kotys:
https://books.google.com/books?id=-D6BP ... &q&f=false
Jeffrey Henderson's Loeb volume 5 of Aristophanes (2008) is devoted to the fragments of that comic writer:
http://www.hup.harvard.edu/catalog.php? ... 0674996151
There is also a Loeb of the fragments of Cratinus. I haven't looked at it.
Eager to hear what you come up with!
You may want to poke around in commentaries on Plato's Republic, since that dialogue opens with Socrates describing how he went down to the Piraeus to the festival of Bendis.
Some recent books that talk about your "new" cults are:
https://books.google.com/books?id=T6Nma ... os&f=false
https://books.google.com/books?id=-2O84 ... os&f=false
(In the above, Robin Osborne argues that Euripides' Bacchae was not inspired by the advent of the cult of Sabazios in Athens.)