All information, including electrical data, e.g. specification of I/O ports can be found can be found in the user manual.
It doesn't make much sense to ask for an output power, although a power value can be calculated form pin voltage and current. I/O pins are providing logic output, to drive a load requiring more power, e.g. a relays, lamp or a motor, you'll use a power driver. But the available output current is specified in the document. Take care not to exceed maximum ratings, otherwise the part may be damaged.
All kind of data can "go out" from the output pins, at least all protocols that can be represented by regular I/O pins, e.g. UART, SPI, I2C. Some microprocessor pins are designed to support specific protocols, e.g. USB.