The filefish might pick at your nem, actually...remember what they eat in the wild. As for the angel, it may or may not interfere with the OSFF's feeding, and personally, I think the only thing that should be in the same tank as nasty damsels (clowns are damsels) is a good-sized lionfish...then again, my opinion of clownfish tends to precede me.
We've had our OSFF for over 4 years, and we partially attribute this to them being in a species setup until they are well-established. Our female will actually eat from Renee's hand now. We did finally add a single P. flavoguttus anthias to the mix as we tore its tank down, and it was the last of a trio that killed each other off. The anthias is shy, but the OSFF are not (they swim around our hands in the tank).
I'm not trying to discourage you, honest, but OSFF require some work and dedication for you to be successful with them, and establishing them is HUGE. Again, once established, they're pretty hardy.
HTH
