The maximum frequency of operation for the SN74HC540N is 100 MHz.
Yes, the SN74HC540N is compatible with 5V systems, but it's recommended to use a voltage regulator to ensure a stable 5V supply.
The SN74HC540N has a thermal pad on the bottom of the package, which should be connected to a heat sink or a thermal pad on the PCB to ensure proper heat dissipation.
The maximum current rating for the SN74HC540N is 25 mA per output, and 50 mA for the entire device.
The SN74HC540N is rated for operation from -40°C to 85°C, but it's recommended to derate the device for high-temperature operation to ensure reliability.