What kind/Blend/type of brass are these made from ? % of copper, zinc then what else added -lead, tin, iron, aluminum, silicon, and manganese?

Hello and thanks for asking. The long story is that when a column is not completed for material, Amazon subs Blend since it does not know what the material is. This Brass Drift Punch Set is brass, all Brass. Thanks for letting us know so we can update the information.

What is the country of origin?

Mine were made in USA. That was a while back, but even made in China could be ok(price may reflect, USA are more). The other option is to search ebay for only vintage brass punches, it would be your choice. Mine worked great.

Should I use a steel hammer or buy a brass hammer?

These brass drift punches can be used with steel hammer

Good for motorcycle rear wheel bearings?

Hello, the Mayhew Tools 61360 Pro Knurled Brass Drift Punch Set, 3-Piece, would be serviceable at that. The brass makes it perfect for preventing marring/scratches. However, the appropriate size punch depends on the motorcycle.