The maximum operating frequency of the SN74HCT14DR is 30 MHz.
Yes, the SN74HCT14DR is compatible with 5V systems, but it's recommended to use a voltage regulator to ensure a stable 5V supply.
To prevent oscillations, ensure that the input signals have a fast rise and fall time (>10 ns) and are not slowly changing. Also, use a pull-up or pull-down resistor to define the input state when the input signal is not present.
The SN74HCT14DR can sink up to 6 mA and source up to -6 mA per output pin.
No, the SN74HCT14DR is not compatible with 3.3V systems. It's designed to operate at 4.5V to 5.5V.