You've asked some intruguing questions. I personally have not shot one before but I've encountered them more than I would like to while deer hunting.
How easily they spook depends on many things but as a whole they spook quite easily. But their eyesight isn't as keen as a deer and therefore I have had them walk right up to within a few feet of me while I stood still - wind at my face.
If prompted and you piss them off, they will charge. I suggest you give them the right of way. I've seen one circle in behind a hunter, who wasn't paying very close attention and get charged from behind.
Don't believe some of what you hear about how moose are innocently slaughtered. They can be a clever and difficult animal to hunt.
I believe that the more they are hunted the more difficult it is becoming to bag one.
Many hunters will road hunt in remote woods roads, until they spot one in a clearing etc, and give chase from there, but more and more you hear about hunters persuing them the same or nearly the same as deer.
Hope this helped some, ambush