Hey Michael, good to virtually see you again :)
1) Yes, I use Truffle + Ganache + Rinkey, Remix, some contracts from OpenZeppelin + I also teach my full development setup in the course
2) Nope, my company has a several private independent auditing companies doing audits
3) All DApps are connected locally to our SDK handled, blockchain node and if not we have a gateway exposing blockchain calls via an Go API over HTTPS
4) Nice question, I do to lock value in smart contract between 2 parties meet all the smart requirements of an exchange
5) It's an improvement to PoW but not gonna work imo. because PoA is superior, IMO
Let me know if you have any more questions! :)
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