A few librarians responded:

1. I would say that ideally you would need to contact someone at NYPL in charge of collection development. I checked the American Library Directory, but did not find such a person listed in that directory. However, it would also work to contact the system director, Susan Kent (212-642-0120, skent[at]nypl.org) or the branch directors, Inwood director Judith Rodriguez (212-942-2525 jrodriguez[at]nypl.org) or Washington Heights director Avril Opinante (212-923-6054 aopinante[at]nypl.org).

2. I spoke with one "higher up" librarian and it is not usual for the branches to accept partisan periodicals or other materials. Some people have even tried merely to have a stack of freebies available by the door, but the library won't accept them. Purchasing a subscription is a different story, but, as an NYPL librarian, I don't remember the International Socialist Review being on the list. The best solution is to contact the libraries directly to see how open they are to making this information available.

Please also see the answers to another question submitted to Radical Reference, about starting an anarchist book collection:

http://radicalreference.info/node/703