Rio Grande carries 1/10 silver-filled fabrication metals, made with .925 sterling. We find that the additional thickness better serves fabrication techniques such as cutting, forming, polishing. Rio Grande offers single-clad sheet as well as round, half-round, and square wire. Wire is available in both dead-soft and 1/2-hard tempers.
Be sure to use silver solders when soldering silver-filled metals, and avoid using hard solder. Coat your piece with barrier flux to prevent fire scale. All the regular fluxes that help solder flow will work fine: My-T-Flux, Handy Flux and Jel-flux. For pickle, use Rio Pickle or PickleIt. It might not remove the stubborn pink stuff from the brass, but it will clean the silver very nicely. Sanding or rubber wheels work well to remove the pink from the brass. PS: Balling up the ends of the wire is not a good idea. It's difficult to do (the silver melts first, then the brass) and it looks pretty bad.
THe FTC has not approved any quality mark for silver-filled metal. The best course of action would be to omit making any quality mark (at least until a legal agreement is issued by the FTC around what a proper mark should be).
Finish silver-filled metal as little as possible. Tumbling in steel shot is a great way to put a shine on silver-filled pieces, because it's a non-abrasive finishing technique, and there is no chance of removing the silver layer. Keep in mind, though, that steel shot can't remove scratches. Conventional polishing with abrasives should be avoided if possible. Using sandpaper, rubber wheels, polishing compounds, etc., removes silver and may expose the underlying brass. Oxidizing is okay, because silver-filled metal will oxidize just like sterling. Black Max or Liver of Sulfur both work great.