@tpmccallum Thanks! Let’s find a place to put these Q/As on the website…
Nope! I believe FourthState Labs was working on an account based Plasma chain. It’s entirely feasible, although it’s a little more complicated than a UTXO chain.
Lots! It seems like most projects are starting off with PoA for simplicity but are planning to move to PoS or something similar once their designs are off the ground.
Of course - It would probably be weird if the operator were actually a person. I’m guessing almost all (if not all) “operators” will really just be a machine that automatically selects transactions and submits blocks.
All Plasma designs require that at least something is validated, but it doesn’t necessarily have to be entire blocks (see Plasma Cash).
In the sense that users can (and should) validate the chain without participating in the consensus mechanism.
DELEGATECALL isn’t a requirement, but it could be useful in certain circumstances (contract upgrades). I would think about the use case before selecting your language.
I’m currently writing some new material about this. Gist is that we have to change how we think about smart contracts to make them really work inside Plasma, but I don’t think it’s unfeasible.