https://steemit.com/faq.html is a great place to start. I picked up most of my knowledge reading posts written by developers/witnesses. It all happened organically and my knowledge about the blockchain is only "Above Average".

Here are few more cool tools to check out: https://helloacm.com/tools/steemit/
A little old post of mine: https://steemit.com/steemit/@vimukthi/sharing-some-of-my-steemit-wisdom-after-228-days-and-1000-followers-a-collection-of-tips-useful-sites-apps-built-on-steem-and

Great place to learn and observe stuff created by @drakos: https://steemian.info

The difference between SBD and STEEM is that SBD has a price floor of 1 USD. In any case SBD price go below 1 USD, you can buy some in the market and convert each SBD into 1 USD worth STEEM. That's how it was designed to be. You can't buy VESTS with SBD you need STEEM to power up. Other than that they are mostly similar things.