Diana Walstad is the originator of this idea and wrote the book, "The Ecology of the Planted Aquarium" so she's the expert, but I'll give you a concise preview:
1-1.5" of unfertilized (generic works best) potting soil
1-1.5" of gravel on top
Use at least 1.5Watts/gal of lighting PLUS some natural sunlight from a window.
Allow some plants to grow emergent or have floating plants like duckweed, salvinia, water lettuce. This keeps algae in check by giving some plants exposure to air (and thus CO2).
No fertilizers, CO2 or other additives are needed. The soil provides a myriad of beneficial bacteria, nutrients, minerals that keep the substrate from producing toxic gas like H2S etc. The plants get all nutrition from the soil and generous feeding of the fish. CO2 is provided by decomposition in the soil.
Others can probably give a better explanation, but this is a start for you. I can attest to the success of this method. I have the tank I've always wanted (lush jungle!) with no expensive products or heavy maintenance, and best of all---no algae problems. I'll attach a photo of it taken in its jungle incarnation.
EDIT: I see I left out two issues you asked about. Water changes are rarely needed. Every few months maybe. I've read of some doing only 2 a year! Filters are not neccessary since the plants filter the ammonia and nitrite out of the water, but you can use them for water movement and mechanical filtration---if you want. I think Diana suggests powerheads only for larger tanks. I have no filter in my little one gallon, and I use the Hagen mini submersable in my 10g for water circulation.