Alright, Lightning... Just so we can throw some numbers out there:
How fast does lightning travel? An average bolt of lightning travels at 224,000 MPH. 3,700 Miles Per Second and if we put that on an even smaller scale; the actual strike lasts about 30 millionths of a second.
How hot is lightning? Lightning can rapidly heat the air in its immediate vicinity to about 20,000 C. (36,000 F.) Lets just say the sun's surface temperature is 5505 C. So an "average" lightning bolt for that split second is 4x hotter than the surface of the sun. Positive lightning can even reach temperatures 5x hotter than the surface of the sun.
Now that that's said what about charges? You see lightning can be Negatively charged, or Positively charged.
Which one is worse? That would be Positively Charged Lighting, this is usually the cause of most forest fires. Just to put it on a scale the average positive lightning is 10x that of negative lightning.
How does lightning kill you? What kills you are the amps, and how many amps does it take to kill a person? The answer is as low as a few milliamps passing through your heart.
Thunder? Thunder is a result of the super-heating of the surrounding air, this is in fact two booms. Just as in sonic jets, once you reach the sound barrier two resounding booms will echo through the surrounding area.
Then why do people survive? That is because most the time lightning travels in two paths through a human. That is the surface of the skin and the pathway through your body. After a lightning strike some people have damage to their outer skin, consider yourself lucky it didn't pass through your heart. Lets just say an average "Negative" charge of lightning carries about 30,000 Amperes 30(kA) Remember it only takes a few milliamps passing through your heart to kill you?
You see lighting is attracted towards the ground, now this also has a negative/opposing reaction. That is what in the science community calls "Sprites." See ---> http://en.wikipedia.org/wiki/Sprite_(lightning)
How does lightning form? I could go on and on about ice crystals rebounding off graupel and causing super cooling, thus the generation creates a positive charge... But the clouds gain a positive charge! After that it has to wait for a golden path of ionized particles to lineup and create a pathway from its position towards however close it can get to the ground.
Just to be clear only 20%-10% of lightning strikes actually hit the ground.
Does lightning help anything? Yes, in fact just to name one, "Plants." Plants need nitrogen to grow and the air is about 77%-78% nitrogen, (give or take) but the nitrogen is in a form plants cannot use. Lightning however transcends that barrier and preforms a process we call "flxation" of nitrogen. Although... Lightning only provides about 5% of the natural flxation of nitrogen. Bacteria doing most the work...
I hope you learned a bit about lightning. xD if you didn't find it too boring. Anyone can correct me if I miss wrote any information.