When shooting indoor sports, I find that the best way to get consistent results is to use manual mode in Auto ISO. I shoot Nikon with the same fairly slow 70-300mm lens. Reiterating what Dennis said, I set the aperture to wide open (f/4 at the 70mm end), and set the shutter speed to something that will freeze the action. The camera picks the ISO and since the aperture is always wide open it holds the ISO as low as possible. If I want to change it up to blur the action I can adjust the shutter speed slower and then I get lower (less noisy) ISOs.
Are you using spot meter mode? If so, that may drive you nuts with white ice and all the black uniforms. White will cause your camera to under expose and make the white ice look grey. Black will cause your camera to over expose and make black look grey. Google "exposure compensation for snow" for all the details on why that happens. The Canon "evaluative" mode may help with this problem since it will expose for the entire scene.
If you still have problems with getting inconsistent results use Dennis' suggestion of using a few test shots to get everything dialed in, including the ISO. (turn OFF auto ISO) In this case, with the 70-300mm lens, set your aperture to f/5.6 so that it stays consistent for the entire zoom range. Pick a shutter speed that freezes the action and an ISO that give a nice bright exposrure and stick to it. If you want to play with blurring the action and panning shots, slow down the shutter and take a few more test shots to dial in the ISO and shoot that way for a while.
None of your photos look bad and many look great. You may also be having trouble with nailing the focus. I have the same problem in lower light situations with that lens. If you nail focus the lens is very sharp, you can see the threads in the patches on their uniforms, but its tough to get that every time. If Scott Thomas chimes in on this thread he may be able to shed some light on getting the focus issues worked out.
Rent yourself a 70-200 f/2.8 and all your troubles may go away! (+1 for lensrentals.com)