I have recently purchased and set up a 6 gallon Fluval Edge. I set it up with Eco-complete planted aquarium substrate and added a small amount of gravel to the top layer (petsmart brand) well rinsed along w a red lava rock soaked prior to reduce cloudy water. Two days later I had the PH reading 7.0 and the temp at 76 degrees. This was Saturday, I figured it would be a good time to visit an aquarium store and purchase or at least plan my setup. At this time after relaying the temp and ph I was told it would be ok to buy plants and some basic fish. Please see photo. I bought a moss ball, a sword plant, a plant I cannot recall the name of and a bit of algae. In addition to my plants I purchased 6 neon tetras and 2 small angel fish* pic and some ghost shrimp that are difficult to count but so far i've counted ten. I have the Fluval filter that came with the tank, no heater, and an external thermometer. Currently the temp reads 79-80 and the PH tested at 7.0 with a basic kit.

Yesterday I clearly overfed the fish as there a bits of flakes stuck on the leaves of some plants that no one seems interested in (resolved-eye ball sized portions, giving them a day of fasting) but I noticed last night a clear mucous like growth on a rock that today has become larger and has sprouted a twin.

I am hugely concerned that I will cause my fish to die or become ill by not educating myself.

1. What can I do to rid the tank of this clear mucous? *Overhead pic on rock by tetras and slightly to right on bulb
2. Have I overpopulated my tank w shrimp?
3. How often should I change the water?
4. How much of the water should I change? I know that I must purchase a more complex water test kit and a gravel suction cleaner (on the list for tomorrow).

Any advise is GREATLY appreciated. I didn't buy these little guys to hurt them :(