Nice find on the Nishiki! you got a good deal, especially in Brooklyn. If your worried about the paint, powdercoat is the way to go, should run about $100 for the frame and fork. Other than that, I second a good lock, run a cable through anything that has a quick release, and possibly a rack and fenders if you think you could use them. Deffinetly lights, and since you mechanically inclined(assuming by your Celica), check out sheldonbrown.com to learn how to fix anything you can't figure out how to do on your own. Also, check out the classic and vintage forum here, your bike would fit right in there and I'm sure someone could tell you all about it.