Rusty fasteners are probably best replaced. You can clean them up cosmetically, but if rust has begun in the threads, they could rust in place. Then you could have to drill them out, which is a PITA at best, and risks damaging whatever they're threaded into. There's a good possibility you can find equivalent fasteners very cheaply at a local hardware store or Lowe's, if you don't need them to look bike-worthy.
Rusty spokes... depends on how rusty. Some little spots shouldn't be any problem to buff out. But again, if they're rusted enough to be weakened, you could be at risk for breakage. How much of a problem it is for you to break a spoke depends mostly on where you ride, somewhat on your skills and what tools and parts you carry.
Scotch-Brite pads are usually your best bet for cleaning up metal while removing as little good metal as possible.
Last edited by OakLeaf; 11-03-2009 at 04:37 PM.
Speed comes from what you put behind you. - Judi Ketteler