If the ice in your freezer has a funny or stale taste, so will your drink. The easiest thing is to pick up a bag of crushed ice at the store.
Cheap blenders have a tough time blending all the ice.
Instead of turning on the blender and letting it run, pulse it on and off until you don't hear anymore ice chunks. For lower calories you can even use water. You can add flavored syrups or fresh fruit to enhance your drinks. I just love the White Mocha with fresh raspberries. I've been told that Kahlua is great in the Mocha and Captain Morgan's rum is tasty in the White Mocha.