The first circuit is the power source.

The 3,3V for the device is delivered by an mcp5504-3 LDO voltage regulator. This regulator is chosen, because it got an enable input. This input is fed by the NCP300 chip, who gives out an high signal, as long the cell-voltage is above 3,2V. This protects the cell from deep discharge and ensures the voltage is always high enough for the circuit.

The MCP73831 is a programmable (via R2) lipo charging IC used for safe charging of the cell via the micro-USB port.

The little bridge on the switch is because the cell can be used and charged simuntaniously.