OH, you all are so cute, and clever, and smart, and fun! I was hoping for at least one encrypted message that I would be able to understand for a change before someone posted the entire answer key for all to see, lol. And, no, I'm not so smart, the only reply I understood was the oil weights, lol.
The 5 x 5 was just a hint for a simpler visual aid in the form of a grid with the letters A-E down the left side and the numbers going across the bottom.