Willy L--I have seen coyotes stand on their hind legs to enable them to look over snow drifts and little hills. They use every resource they have to survive, and believe me, they have plenty of resources!!!
As far as the spinning motion after a coyote is shot, I have seen it many times. Most of the time it is a "death spin" and they collapse and expire. On Februay 2, 2004, the coyote I shot when it was -24º, had the bullet enter right between her two front shoulders (actually closer to her left shoulder than the right) and the only visible blood was a little bit in her mouth. She did hump up and begin to turn her head around slightly when the bullet struck, but didn't do a spin. When I got up to her (a walk of about 160 yards), she had her left front ankle squeezed tightly in her mouth. I think they bite at the area they feel the pain in. All that adrenalin they have pumping keeps them physically going even whey they are dead on their feet.
One thing I have noticed that when a coyote does the death spin and if they are yelping at the same time, their mate/s will sometimes come right on in to give you a closer shot at them just from the yelping their mate is doing. I have definitely incorporated the wounded coyote sounds into my bag of calls for bringing other coyotes in after I have shot one or two. Even if it doesn't bring them back in, it is usually a sound that will make them slow down or even stop so you can get a good shot at them. If I am thinking quick enough and have the FoxPro with me, I'll start the Coyote Pup in Distress sound at pretty high volume and that works to get me another shot (usually).