Are ratings (volts and amps) inter-changable on components?
Absolutely not.

The voltage rating is generally based on safety concerns and insulation properties. The current rating is based on the wire construction (thickness), and heat dissipation properties.

For a switch, even the AC and DC properties might not be the same, as any arcing that occurs in an AC use is quenched 120 times/s, while in a DC situation it is not.

Generally less than 40 V or so is reasonably safe for bare contact with one hand, but you would certainly feel 40 V if you touched it with wet skin (I wouldn't try it) -- you might even feel 9 V.