Sony Ericssson - HBH-300 power supply

I bought a Sony Ericsson - HBH-300 headset from the U.K. and of course the
power supply came with the standard 3-blade UK plug.
I've ordered a plug adapter and have since jerry-rigged my own by taping the
leads from an extension cord to the blades of the adapter.

My questions are:

1. Is there a US plug version power supply for this headset?
2. Would the power supply for an Ericcson cell-phone work? (.e.g. T-39)
The plug to the phone and to the headset look to be the same, but I
don't know if the power supply output for the phone would be
compatible with the headset.
3. Likewise, would a standard Ericsson cell phone car charge work?

All replies and suggestions are most appreciated.