What give value to steem?
Users and Resource Credits(you need it to interact with blockchain).
What is quality content?
Post that help solve problem... Tutorial, testimony, ask, opinion, recipes, photography...
How onboarding the mass?
Friendly UI(More Options), easy and fast registration, mobile app...
How to solve the creation of multiple accounts by the same person?
Mobile app, an account for smartphone.
How solve the plagiarism?
Put a check box asking if his content is original content.