re the whole facing thing. When I bought my Troll used, I stripped it down to the frame, partly to learn about the new to me hollowtech2 bb type, and also to go over everytihng myself to know what shape it was in, and to regrease everything.(and I put framesaver in the frame too)
I didnt get it faced, bb or headset area, and so far its been fine, so I guess it was nice and parallel everywhere.
maybe with a new, painted frame, its worth it, but probably worth asking a trusted mechanic about that, probably worth the small fee to get it done if not sure.