Hi whoeverishidingbehindPanda21andseemstoknowme, 
Those are quite a lot of questions and to answer them fully would take a lot of time which at the moment I do not have. Also very few people will read this answer and my main reason to post on Steemit is to spread knowledge. So it would be better to devote a post in my blog on the issues you mention.
Fortunately I have already covered a few...
- I think I will do a post on lightning later, so I will skip that question for now.
- I know ElectroBoom and generally like his videos. Unfortunately he is ill-informed on Tesla and so he spreads poor info on him. He certainly did not generate millions of volts in his home. A few tens of thousands at most. :) I have commented on some of his videos.... :)
- In [this post](https://steemit.com/science/@mage00000/tesla-s-dynamic-theory-of-gravity) you can read about my idea about Tesla's theory of gravity. And yes, Tesla proposed to use magnifying transmitters to supply power to flying vehicles.
- The earth is a conductor, and since Tesla showed that you can transmit power over only one wire, you might as will use the earth as that wire. In [this post](https://steemit.com/science/@mage00000/tesla-s-magnifying-transmitter-part-4-power-distribution) you can read more about it. 

I hope that covers your most urgent questions :)
Always happy to see some enthusiasm!