ML
Yes when I bypassed the waterfall, a pipe 3-4 inches under the surface would force the water from the filter up to the waters surface. This would agitate the surface a little and create a little current.
As far as water changes. A micro pond is like a giant Aquarium. Get yourself an aquarium test kit Ammonia, Nitrite, and Nitrate.
You Will want to monitor the ammonia and nitrite for the first couple of months. Low levels are normal in a new aquarium, but if their levels spike do a partial water change (20 - 30%). By keeping your original numbers of fish to about 50% of carrying capacity and not overfeeding you shouldn't have any Ammonia or Nitrite spikes.
Once your micro pond is "cycled" Usually 4 - 8 weeks the amonnia and nitrites will disappear and you shouldn't have to worry about them much as long as you don't overfeed or add too many fish at once. Eventually, You will just check for Nitrates. Nitrates are an indicator of water quality and will tell you how often you will need to do a partial water change. It really depends on the biological load you put on the amount of water in your micro pond. Good luck and keep us posted!
