I bought a locomotive roster book at a hobby shop a few years ago it had Metro North listed. If you check at your local hobby shop or on e-Bay you should be able to find a roster. The listings in the book I bought are fairly limited. They list mainly unit #'s, type of locomotive, horse power and year the unit (s) were built.
As far as photos I have a few shots of MN locomotives from some trips I've taken down there over the years, mostly on the HUdson line with 2 or 3 on the upper Harlem. Unfortunately they are mostly prints and I don't have a slide scanner for the ones that aren't. I have a flatbed scanner and I could try to send you something you could use.
In a perfect world CONRAIL and the FL 9 would never die !!!