1. https://www.investopedia.com/terms/p/proof-stake-pos.asp Yes, proof of stake is exactly that. 2. Read the above comment and search some of those companies 3. Binance props Tether up, so the largest Centralized exchange may suffer dramatically, but a Tether collapse would likely drive users into better stablecoin projects like USDC and DAI, being generally good for the space