Don't think for a minute freezing at the top of a cloud is the same temperature that water freezes at the earth's surface. At any rate, ice forms at the top of the cloud and we can have all kinds of interesting phenomenon such as hail, rain, lightning, and down burst. Wind shear is change in wind speed with direction and height. Most of the rain in thunderstorms is melted hail. When the cumulonimbus cloud develops it's anvil, it is also when lightning develops do to processes beyond the scope of these notes.
Lightning can strike between cloud and ground, cloud to cloud and inside the thunderstorm itself.
All thunderstorms have downdrafts at some stage in their lives, but microburst, also known as down burst have winds of 57mph or greater. This down draft of cold air is caused by storm hail falling through the cloud and forming a large area of cold air. High dew points are a good indicator of instability, CAPE is a direct measure of instability. CAPE stands for Connective Available Potential Energy, and is directly related to how warm air parcels are in relation to their surroundings at all elevations. As air parcels rise, latent heat is released.