The phrases "we may live" and "not die" mean the same thing. Judah is emphasizing that they have to buy food in Egypt in order to survive. Alternate translation: "We will go now to Egypt and get grain so our whole family will live" (See: [[rc://en/ta/man/translate/figs-parallelism]])
Here "our" refers to the brothers. This refers to the small children who were most likely to die during a famine. (See: [[rc://en/ta/man/translate/figs-exclusive]])