Re: calories burned walking 18 holes
Your mileage may vary (literally) but here are some empirical numbers for comparison. I played 3 rounds over the last the week or so on 3 different courses, walking, carrying clubs, and wearing a Garmin Forerunner GPS watch & heart rate monitor that converts measurements into calories burned.
I carry 14 clubs in a Ogio Grom bag. A large bottle of water or Gatorade I refill at every opportunity, 8-10 balls, laser range finder, a wind breaker, and a smattering of tees, markers, gloves, band aids, etc etc. I drive a desk for work and am in pretty lousy shape at 195lbs.
1. North Park Golf Course: 4:03 round time. 6,440 yard listing. 6.6 miles walked. 546 ft of elevation gain. 1,453 Calories Burned.
2. Moon Golf Club: 4:03 round time. 5,404 yard listing. 6.1 miles walked. 555 ft of elevation gain. 1,217 Calories Burned.
3. Ponderosa Golf Course: 4:18 round time. 6,283 yard listing. 7 miles walked. 512 ft of elevation gain. 1,362 Calories Burned.
So the short answer is "it depends" but for me, 1,200-1,400 looks like a fair estimate. I have a couple 9 hole rounds that also fall in that range.
Sorry, but I don't have comparison for riding a cart.

-TiNB
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Edit to add weather information:
All 3 rounds in low 90's, high 80's weather, about 75% humidity.