Decals are avalaible. Either through Waterford (formerly the Schwinn Paramount builders) or through a reproduction decal producer such as velographics (contact mswantak here on BF's)

Rear wheel rebuilds aren't going to be too pricey, and if you're thinking of going 700c then might as well pick up a new wheelset anyways (see next point)

Going 700c is usually an option. The difference in radius of 27" vs 700c is 4mm. Which means if you can drop the brake pads 4mm then you should be able to fit the 700c rim no problem. If you can't get this much drop out of the current brakes, there may be longer reach brakes out there that can do the job.

Vintage Nuovo Record derailleurs are out there, and fairly common on ebay. They command a decent price, but certainly not out of sight (unless they are in NEW condition). I'm guessing around $30-$40 depending on condition and year.

Mod note: merged the duplicate threads together. Enjoy the Schwinn!