Question 1: The important thing is to stay hydrated, in most cases the person becomes dehydrated. You can overdose but each person can be a little different, the only way is to see how your body reacts.
Question 2: Yes you are correct on equal amounts, I'm no chemists but I'm pretty sure thats the formula.
Question 3: You can always cut the juice with non flavored juice, distilled water or vodka. It might thin out the juice if you use water or vodka, remember it must be distilled water.