The specs aren’t listed on the FDK site but the safety
data sheet shows it is a 3V battery although amperage is
unclear.
All lithium-ion batteries have a nominal voltage of 3.7V, like how all alkaline batteries have a nominal voltage of 1.5V. It's just how the chemistry works.
And to be somewhat needlessly pedantic: you want "amp-hours" there, not "amperage". Amp-hours is the unit of capacity, amps is how much current is being drawn at that very moment. In the automotive metaphor, amp-hours (or watt-hours) is how big the gas tank is, while amperage is engine horsepower.
(Actual voltage can vary quite a bit, depending on where you are in the discharge curve: http://i.stack.imgur.com/UkodS.gif)
And to be somewhat needlessly pedantic: you want "amp-hours" there, not "amperage". Amp-hours is the unit of capacity, amps is how much current is being drawn at that very moment. In the automotive metaphor, amp-hours (or watt-hours) is how big the gas tank is, while amperage is engine horsepower.