Actually this is quite concise in my opinion though I have few suggestions about each point:

2. With Investopedia maybe ? They have tons of great articles but they lack the fun and living part (which you can compensate!)

3. Like you said, you want to be laser focused on one thing and one thing only : teaching. Maybe you can partner with RobinHood ? Just don't do it yourself.

4. This. I would definitely pay for it.

5. Nope nope nope, as a young platform you want to get people come see you so I suggest maybe organizing some kind of competition where participants have to pay a fee, you take your % and you give the winner(s) the rest.

6. Sponsorship = good. Advertising = bad.