Looking to buy second lens at fair price... recommendations?

[Mark Sawyer]

also would someone be willing to explain the difference between the FS Rodenstock 210mm Apo Sironar N and the 210 Rodenstock macro sironar? someone is selling the former in the listings

The Macro Sironar is optimized for focusing at macro distances. You might want to read http://www.largeformatphotography.info/macro.html for some basics.