Combine 6 cups water and farro in medium saucepan. Bring to boil. Reduce heat to medium. Cover partially; simmer until farro is tender, about 20 minutes (about 45 minutes for wheat berries). Drain well. Whisk oil and vinegar in large bowl. Season with salt. Add farro, toss and cool.
Meanwhile, cook favas in pot of boiling salted water for 3 minutes. Add peas and cook until just tender, about 1 minute longer. Drain. Cool in bowl of ice water. Drain. Add favas and peas to farro. (Can be made ahead; cover and chill).
Add arugula and tomatoes to farro mixture (and basil if using it). Toss to combine. Season generously with salt. Spoon salad onto platter. Garnish with additional arugula and serve with parmesan or pecorino cheese.