Not sure who is confused more. Tire guy or you.
First, it's just too hard to look at your current tires and see the load rating, or use the internet, I guess?
275-70-18 E is a common OE size they are (all) 125 load rating or 3638lbs rated.
How soft or harsh a tire rides is 90-95% air pressure and very little to do with it's load rating or treadlife.
Price for the tire you picked out is not horrible. Online they're about $280-$310. Again something you can find out yourself pretty easy with the ole googler or calling other tire shops.
