3- In the future, the ideal scenario would be to post a script on the Bitcoin blockchain to deploy what could be called an "oracle." This way, even if the price comes from an average of multiple prices from centralized or decentralized platforms, it will be obtained in a publicly verifiable manner.
I see. But Bitcoin script cannot interact with external system without relying on 3rd party (which act as Oracle). That means some degree of trust is required and i expect some people might say your lottery isn't really decentralized. CMIIW.