Stir together first 6 ingredients. Cover and chill 30 minutes.
Shape chilled crab mixture into 12 patties (about 1/3 cup each). Place breadcrumbs in a shallow dish; dredge both sides of patties in breadcrumbs. Fry patties in hot oil, in batches, in large skillet over medium-high heat 2 minutes on each side or until golden. Drain on paper towels. Place 1 crab cake on bottom half of each roll; top each with arugula and a dollop of Dill-Caper Cream. Cover with top halves of rolls.