Great to hear you got a FED-2!
Zenit SLR lenses will mount but won't focus correctly at all. All Leica thread mount (LTM) lenses will work, except for pre-war FEDs.
I've had no major trouble with mine, knock on wood. My first one had a bad light leak around the film gates, which I was able to fix easily by bending the metal back into shape, and on both of mine I've used thin strips of electrical tape to keep the diopter controls from wandering.