Little Terrace falls are further downstream from the main Terrace Falls and past the Salote Pool, not far and an easy walk but if Terrace Falls are flowing, then these falls will have a nice cascade of water over them as well. The falls are perhaps 8mtrs in height and tumble into a sandy pool at the bottom in the traditional partial bowl open amphitheatre that is pretty common throughout the Blue Mountains.
I cannot see why you could not swim here, the bottom seems to be a mix of sand and large rocks, so treat it with care like any wild swimming hole.
If you continue downstream, you will come to Bedford Creek, you can turn right and cross the creek you just followed downstream and walk the short distance to Willawong pool, or turn left and head down to Bedford Pool and up to Pyramid Falls.