Beginner to Bit Coin with Questions

1)How did Bit Coin gain traction? Who were the first participants? Which businesses agreed to trade on Bit Coin at very beginning?
2)What is the main growth mechanism of bit coin value?
3) Would Bit coin users stagnate in future or now?
4) How has the Bit Coin Trading changed? What new businesses trade on Bit Coin?
(One person need not answer all 4 questions, just say which question you like to answer and answer it)