Loco-Deer-SlayerI know it's not on your list but trampolines are one of the best tools to train. It works on balance, builds muscle from explosive movement, and it's cardio.
Out of running and biking, biking is way more low impact on the joints. It depends on the person but I can't run before a day I ski. One thing running does have over biking is you can choose to train at altitude. You can definitely do that biking but your options are more limited.
Running at 10,000 ft plus will whip your ass into shape real quick.
I second this. It also helps your air sense. A coach told me once, "Your body is really not used to floating in the air, you need to be up there as much as possible in the off season to get used to it."