Co2 Cartridge?

I work at a bike shop that sells 16g non-threaded co2 cartridges which is what im looking for my tap a draft system. is there such a thing as food/beveage safe co2 or is it all the same. i know the cartridge is the same just curious about the content inside.

Same.

Any way that you can put some tubing where the cartridge goes? Then use a paint ball tank and regulator. Much cheaper.

I thought that some of them contained oil ?

The ones for BB guns have oil, not sure about bike cartridges.