Newtown planners have approved a new retail plaza on Route 6 near the Bethel border for a Danbury-based business. The family-run company plans to build a 4,400 square foot commercial building with 22 parking spaces on a one-acre wooded site near the busy Stony Hill Road corridor. Company officials say construction could begin once the property sale is finalized. The area has seen increasing development activity in recent months, including proposals for housing and medical projects nearby.