All 3 questions mean basically the same thing. They use these questions to emphasize that there is nothing they can say to explain what happened. AT: "We have nothing to say, my master. We cannot speak anything of value. We cannot justify ourselves." (See: [[rc://en/ta/man/translate/figs-parallelism]] and [[rc://en/ta/man/translate/figs-rquestion]])
Here "my master" refers to Joseph. This is a formal way of speaking to someone with greater authority. It can be stated in second person. AT: "What can we say to you ... your slaves" (See: [[rc://en/ta/man/translate/figs-123person]])
Here "found out" does not mean God just found out what the brothers did. It means God is now punishing them for what they did. AT: "God is punishing us for our past sins"
The brothers refer to themselves as "your servants." This is a formal way of speaking to someone with greater authority. It can be stated in first person. AT: "our iniquity" (See: [[rc://en/ta/man/translate/figs-123person]])
Here "hand" stands for the whole person. Also, "was found" can be stated in active form. AT: "the one who had your cup" (See: [[rc://en/ta/man/translate/figs-synecdoche]] and [[rc://en/ta/man/translate/figs-activepassive]])