You run into similar problems whether you're using an SLR lens or a spotting scope.
The green arc in the first photo looks like lens flare - an internal reflection within the lens. Those are almost unavoidable when your photograph contains a very bright spot, but that's not the case here. So I suspect that stray light is getting into the system from the side. The obvious suspects are at either end of the scope. Make sure you have a good hood over the "big end", and see if you can rig up some sort of light-excluding coupling for the "little end" too.
The second image has a couple of problems, but the one that strikes me most is the purple tinge to all the edges. That looks like chromatic aberration. It'll be most obvious when shooting against a bright cloudy sky like this. It will be reduced with a better (more expensive) lens.
The third shot might be out of focus, but I bet the blurring is actually due to motion of the camera/scope. At long distances (except in the most extremely bright light) you need to use a tripod *and* have the camera rigidly mounted to the scope in such a way that you can't move it while pressing the shutter. If your P&S has a remote shutter capability, use it.
Even with a rock-solid tripod setup, your subject may move during the shot if the exposure is too slow. Therefore:
If your P&S has manual controls, you want the fastest shutter times you can get (i.e., high ISO, wide aperture -- once you've got the shot, take a couple more at lower ISO for the most vivid color and reduced noise).
Edit: I usually do NOT shoot in "exposure priority" - if you dictate an exposure of ,say 1/1000 sec, and there's not enough light at the widest aperture, you end up with a badly underexposed shot. If instead you specify the widest aperture, the camera will calculate that it needs, say, 1/100 of a second, and the shot will be correctly exposed. The shot may still be unusable due to motion blur, but every once in a while you'll get lucky and miraculously keep the camera steady. (I usually shoot hand-held; with a tripod "every once in a while" becomes "almost always".)