First off, transaction fees have to be vanishingly small. We’re already there. As of last Nov’s 1.14.5 update, typical transaction fees have been ~$0.003 - which you can experience on @robinhoodapp - compared to the 1-3% network fees that major card networks charge.
7) Because it would all be on-chain, it would be trivial to integrate the following into Twitter:
a) tips/payments/monetization for content creators
b) NFTs/profiles/avatars
c) sure, why not DOGE