Arduino Fio power supply

There are different pins that can be used to power Fio. I get confused: on my board next to the battery connector there are two pins marked + and -, is it there I should connect the regulated 3.3 V? Next to the USB connector there are 2 other pins marked - and 5V, is it just for charging the Lipo battery? Another question: on ebay they sell 3.7V Lipo batteries, do you think they maybe used with Fio? Thanks for your help!