^ generally, yes. Higher cadence in an easier gear will place more strain on your cardiovascular system and less on your leg muscles.
https://www.amazon.com/CAT-EYE-Wired-Computer-Black/dp/B007YV1GFQ
This one will work just fine for you. Don't buy a wireless computer. That means another battery (sending the sensor signal), which is another to replace and an additional failure point.