re: Best way to prevent water from flowing under my pier and bean home?

No sand, will not stop the issue.
No berm, it will retain water under the house.
French drain large enough to hold the volume of a heavy rain like today.
Long term, you will have erosion as water continues to get underneath the home, this will cause structural issues.
Solution- keep it as dry as possible/dry it out as quick as possible- sump pump will do this.

You can call WCK foundations to look at your issues and see what they advise. I am a contractor and this is what I have seen be successful with pier and beam porches and homes