By and large, most people on the planet who have access to the internet also have access to cryptocurrency and that access would be generally hard to censor.

Learn how to deploy and use a DAO. (See e.g. Aragon Project, DAOstack). Probably learn about how to run a governance process — you could study the theory of social choice and voting and/or how other open organizations function.

Generally speaking, blockchains provide the ability to immutably store data but in and of themselves they do not assure validity of that data -- that is the job of the process or protocol that adds the data to the blockchain. As an example, if you are a university and you want to issue and store diplomas on a blockchain, you will achieve immutability -- the diploma will stick around forever, even if the university is shut down. The validity of the diploma may be based on trust -- "I trust Harvard not to lie that they issued someone a diploma, and I know Harvard created this record" -- or other methods like decentralized voting or attestation. If you have a certificate that is immutable and digitally signed by the issuing institution, this is a pretty strong deterrent to impersonation and faking.

There's a whole space of NFTs (non-fungible tokens) which are dedicated to this area. You can read about CryptoKitties, NFT collectibles, and NFT marketplaces like SuperRare and OpenSea.

Certainly. PoW is a very energy-inefficient (but secure) way of reaching consensus in a distributed system. You can use a number of other consensus algorithms to reach consensus, such as BFT, DAGs, and Proof of Stake. Proof of Stake systems, for example, require no special hardware and don't use exorbitant energy, but are much trickier to prove the security of (and to prove security, you need to make assumptions about the network).

Generally speaking, blockchains tend to be transparency technologies. (They also have aspects in privacy as well.) If you can manage to get most economic activity (payments, purchases, investments, financial operations) onto blockchains, and if you can convince the transactors to be transparent about them, then this will probably represent the most accurate real-world measurement of GDPs. That's a lot of if's though. :)

You should look up some of your favorite blockchain projects and contribute to their open source repos! The best resource for an engineer, especially a blockchain engineer, is experience. Ethereum is not going to be the only platform upon which you can launch dApps. Check out Tezos, Cosmos, Dfinity, Polkadot, and many of the other projects which are providing platforms for development.

It's a popular language for the backend technologies that comprise a lot of the node software used to run decentralized networks or blockchains. Rust is also a popular language for this purpose. I would say knowing Golang is a good idea for blockchain and in general.

Well, blockchain has relatively little "backend programming" unless you're programming the consensus layers or blockchains themselves. If you want to pursue this, I recommend learning some backend languages (in blockchain, Go and Rust are popular) and then learning as much as you can about consensus, various consensus algorithms (BFT, Nakamoto, Proof of Stake systems) and find a team which is building a base layer technology. If you want to program the "backends" of dApps, then you're coding a smart contract programming language. The most popular one is Solidity, and there is a large amount of literature on Solidity programming and many deployed contracts have their code available for inspection on Etherscan. If you want to focus on the frontend, there is a large overlap between dApp frontend programming and just JavaScript frontend programming in general. Here, you'll want to learn things like the Web3.js framework, how to connect hardware wallets like Ledgers and Trezors to the frontend, and interacting with the Ethereum (or another blockchain) from JavaScript. All of these activities should be accompanied by a fundamental understanding how blockchains, and probably Ethereum, work underneath. Most blockchain projects are open source and maintain open developer communities that you can participate in. Just pick a project you like and see if they have open bounties (see: Decentraland, Aragon, district0x, etc.).

Congratulations on your progress so far. If you're looking to raise money from blockchain-focused VCs or cryptoinvestors, then you need to get access to them. My advice is to attend quality blockchain-focused conferences and events, ask other founders who they raise from, and pursue warm intros to investors.