USB 3.0 cards are abundant for PCI Express. Models with interna; 19-pin headers are can support front panel USB ports.
PCI Express slots have 25W of power available based on the ATX standards. 5V power tends to be adequate as most power supplies have 25A available.
Both ports are standard USB 3.0 and the Marvell logic is the most commonly used device
The black filters are present to remove transients from insertion and removal of devices.
The transistors are present to convert 12V to 5V. Designs are configured to get power from what is available as many low cost power supplies have more limited 3.3V and 5V current capability.