Nice shots. It would be interesting to know the exif you were using. If you were shooting at 300mm then you want a shutter speed of at least 1/300. I presume the VR will give you a stop or two and you can always up the ISO if need be. The other thing is to practice your panning technique, it's invaluable for birds.
I noticed one image is only about 47k in size, you can go up to 300k which should help the IQ. With regard to USM it's just about playing about with it and checking the preview. This one is with Amount 99, Radius 1.2 and Threshold 0. (oh and I put a small catch light in the eye
HTH.
