Micro BIT power

[Jawloms]

I have an old 3.7v camera battery I'd like to use to power my micro bit. When full I've measured it at 4.1v. I'd rather not fry my micro BIT so 2 things;

 

1. Can I plug it in to the USB to power it or does that require the full 5v through there?

 

2. What is physically the smallest way to wind it down to around 3v so I can power it through the GPIOs? (Preferred)

 

Thank you

 

Stuart