The maximum frequency of operation for the CD74HCU04E is 5.5 MHz.
Yes, the CD74HCU04E is compatible with 3.3V systems, but the input voltage must not exceed 3.6V.
The CD74HCU04E has a built-in power-up and power-down sequence, but it's recommended to follow a controlled power-up and power-down sequence to prevent damage to the device.
The CD74HCU04E can sink or source up to 24 mA of current per output.
The CD74HCU04E is rated for operation up to 125°C, but the device's performance may degrade at high temperatures.