As DMF said, bearing balls are cheap, there's just no reason to re-use them. You can probably get them at your bike shop, or someplace online like
www.loosescrews.com Or at a bearing supply house. Again, you'll need eleven 1/4" balls for each side of the bb. As for the hub, my guess is that someone serviced it before and lost a ball, but don't worry, it's not highly critical to be one short. It would have been better to have replaced the balls there, too, but since it spins smoothly as you say, you should be good to go. The general rule of thumb for the correct number of balls to use is to pack them in until they jumble up, then remove one. Except for headsets, where you should pack them in until they jumble up, and then remove two.
Btw, I started a thread in Classic and Vintage regarding my International a while back, I got some great info and feedback. Here's a link to the thread:
http://www.bikeforums.net/showthread.php?t=256051
Since then, I've found a Regina 14 x 26 five speed freewheel for the bike, and also a very nice vintage 700c clincher wheelset, Ofmega hubs with Mavic Module E rims. Not
exactly period correct, but fairly close. My plan is to lace the Module E rims to the original Campy Record hubs, which are currently still laced to the Fiamme tubulars-
Also, Sheldon has a great website on old Raleighs:
www.retroraleighs.com