Well, you can buy some more java moss if you really feel like it but it probably isn't that necessary. In my opinion, itd be better if u installed a somewhat stronger light but thats just me, because with a light bulb that far... not much is going to grow in terms of plant life. Doesn't have to be expensive or anything, i just have a compact fluorescent screw on bulb + the light socket.
Water changes... since it's the tank isn't cycled yet, do one in a couple of days. So 1 every 2 to 3 days for a week or two, then you can go to 1 a week or so if you're lazy or have better things to do. But considering that you're using a 5 gallon, I can't really say that much. You can get a ammonia/nitrite test kit to test these things (should read 0ppm when ur tank is cycled). But I tend to avoid using test kits cuz I'm cheap/lazy/insert excuse here and prefer to do things by eye. (Not that I don't understand the dynamics behind them.)
Another note: Don't expect the shrimp to start makign babies instantly. They need time to settle in and for water parameters (sponge filter) to stabilize.
