RE: Receiver Output Enable and DE: Driver Output Enable pins
If you only want to receive, then yes, shorting both DE and RE to ground is the way to go.
According to the datasheet:


  Stresses beyond those listed under Absolute Maximum Ratings may cause permanent damage to the device. Exposure to any Absolute Maximum Rating condition for extended periods may affect device reliability and lifetime


In other words, you can connect VCC to up to 18V for a short period of time, but it is not guaranteed to keep working. You should never treat an Absolute Maximums section as a license to operate at those conditions - they should be treated as worst case.

In terms of recommended operating conditions:


  VCC: Positive Supply Input. For RS422 or RS485 operation, 4.75V ≤ VCC ≤ 5.25V. Higher VCC input voltages increase output drive swing. VCC should be decoupled with a 0.1μF low ESR capacitor directly at Pin 8 (VCC)


So it is recommended to run the chip at 5V +/- 5% (*).




(*) Though I'm not sure why LT decided to put that specification in the pin descriptions section rather than the recommended operating conditions table.