The maximum frequency of operation for the SN74HC245DWR is 50 MHz.
Yes, the SN74HC245DWR is compatible with 5V systems, but it can also operate at lower voltages down to 2V.
The enable pins (EN1 and EN2) are active-low, meaning they need to be pulled low to enable the corresponding direction of data transfer. Tie them to VCC or GND as needed.
The propagation delay of the SN74HC245DWR is approximately 10 ns (typical) at 25°C and 5V supply voltage.
The SN74HC245DWR is rated for operation from -40°C to 125°C, making it suitable for use in high-temperature environments.