I am very excited to give this a go! Going to be waiting a bit, and doing more research before giving a Natural Planted Tank a try. Looking into possibly upgrading to a 5.5 gallon tank before doing this project!
substrate matters, more than you think. I highly recommend clay substrates such as ADA's aquasoil (if you can afford it) or Red Sea's florabase. Not only do they provide your plants with essential nutrients necessary for their growth, but they also act as a buffer keeping your pH in the ideal 6.5-6.8 zone which is beneficial for the well being of most aquatic plants. Along with adequate lighting, fertilization, and CO2, well, let's just say the results speak for themselves:
but to answer your questions:
1) yes. better to have than not to have. if you are going to forgo the filter, you should at least have some sort of water pump to circulate the water to keep it from being stagnant (though some fish like this)
2) define complete eco system... you can make the system as complex as you want it to be. benthic invertebrates, swimming ones, snails, hydras (HIGHLY AVOID), all the way up to fish. and yes, a tank of that size can do that.
3) hairgrass, lobela cardinalis, anubias nana, java fern, java moss, cryptocoryne parva, moneywort are all excellent beginner plants. if you want something slightly more challenging, try the Rotala species such as wallichii.
4) online sells a better variety than what can be found at petco/petsmart. try these two places: http://www.marinedepot.com/, http://www.hellolights.com/
I have two 5.5g NPTs, one has been up and running for about a year and the other was just started today. My older one had a Marina slim filter in it for a few months but I have since taken it out, and my new one has a Tetra Whisper in it right now but I plan on removing that in a few months as well. I used Miracle Grow Organic Potting Mix topped with Petco black sand for both tanks.
This is the first NPT I started on 1/16/13
And this is what it looks like now:
This is the new one I just started today
I have 6500K fluorescent bulbs on both tanks. My older tank came as a kit so the hood/light fixture came with it and I just bought a compact fluorescent bulb at Walmart for it. The other has an Aqueon hood and I bought a Zoo Med bulb for it on Amazon. Easy plants that I have in my tanks: hygrophilia corymbosa, water wisteria, amazon sword, duckweed, frogbit, guppy grass, java fern, marimo moss ball, anubias.
I'm not very good at aquascaping but I love jungle tanks :) Good luck with yours!
The Fluval tanks all have filters and such included. Yes, you'll need something, but they all include it. Just need to add a heater... and depending on the tank selection, and plant selection, you MAY need to upgrade the light. The Edge is a gorgeous tank but the design definitely makes some compromises that make working with it difficult (I love mine, but there's no doubt that it's a hassle sometimes). I don't care for the filter design of the Chi. The 5 gallon Spec is a popular Betta tank that does well planted, however.
Full blown co2 systems add an enormous amount of cost and complexity that is definitely not 100% necessary for a very nice NPT... unless you really want to jump in with both feet and love the complications (some people really enjoy the challenge, so that's cool, too). You can have a gorgeous NPT with a simpler substrate, root tabs, and just add liquid fertilizers like Flourish and Flourish Excel.
Amphirion's tank there is spectacular, but a LOT of work went into getting it that way, and that work in ongoing, I guarantee you. G26okie's Spec is a nice example of wht can be done on a smaller scale with considerably less aggravation.