Hmm, I swear I wrote an article on planted aquariums but who knows where it is now
In a Walstad aquarium, you're basically using the plants as your only real source of filtration. Is that what you're looking to do or do you just want a bunch of live plants (but still do regular water changes and have a basic filter). There's a bit less room for error in having plants AND a filter but both can be done in your tank.
More light is almost always better (gives you more options) but the actual brand doesn't matter. Look at the wattage (and also make sure that it's not an actinic bulb or some other specialized marine type). For planted aquariums, I like power compacts. They don't use much electricity, last a while, and are still brighter than regular florescents. In your Eclipse, though, I don't think you have a choice anyways. Don't they come with a power compact fixture? I can't remember, I haven't used an Eclipse in years (well, technically I have one set up but it's just the tank and not the full set-up).
The plants will depend on just how low the lighting is. See what your aquarium is going to come with, to begin. The ideal plants will also depend on the pH (if it's especially low or high, your plant choices a bit more restricted) and what kind of set-up you want (many low light plants should be tied or otherwise attached to rocks and/or driftwood...if you're not looking to use those types of decorations, you need to stick with floating and rooted plants).
Assuming you're using regular potting soil: I sometimes put gravel over it just because it helps keep the plants rooted initially, allows me to vacuum the the bottom without disturbing the soil and roots a lot, and keeps certain fish from kicking up soil all the time (that's not an issue with bettas). But I've also used pure soil, pure gravel, and pure sand. So it's mostly a personal choice and partially depends on the plants you pick (so I can offer more advice once we figure that out). As for picking out a soil, that once again depends on the plants. I've never found substrate to matter all that much, honestly. I've had amazing planted aquariums when the substrate was just plain gravel. Sure, tanks that had specialized aquarium soil did great...but not really any better! Think about the plants you want to keep, what looks best to you, and what's in your budget (there are some really great aquarium substrates out there that are also rather pricey).
You don't move them, there should be no need to. If you feel like you'll need to move plants, keep them potted or use plants that attach to objects or float. Rooted plants shouldn't be disturbed.
I'd suggest doing a ton of reading (that way you can come up with more specific questions, allowing me to help more) and maybe go online "plant shopping"--just to see what's out there and what plants interest you
. Figure out, for example, if you want to utilize driftwood, if you want bright lighting, if you'd prefer a dark substrate, etc.
In case you're interested, I have two betta aquariums set up with the following:
Betta Aquarium 1: 5.5 gallons
-Moderate-low (power compact) lighting (10 watt bulb)
-Small in-tank Whisper (don't use a HOB Whisper with a betta without modifying it, though) filter (mainly there to keep water moving and filter small particles)
-Water temperature maintained at 78 degrees with a heater
-Plants: Various species of anubias and vallisneria
-Substrate: "River" gravel
-Supplements: Very occasional use of Seachem Flourish Excel
-Not really a Walstad aquarium, more like a tank that happens to have some plants
-10% water change every two weeks
-Ammonia: 0ppm, Nitrite: 0ppm, Nitrate: <
5ppm, pH: 7.0
Betta Aquarium 2: 5-gallons (this is the Eclipse) :
-Low lighting (very low...no actual lights, just indirect light from the room)
-Water temperature maintained at 75 degrees, no heater right now (this betta was a gift and not a planned purchase, will have a heater by winter)
-Plants: Anubias nana tied to rocks, tons of java ferns attached to driftwood, a small amount of water sprite floating
-Substrate: "River" gravel
-Walstad with modifications (such as the extreme low light and nutrient-poor gravel)
-Water changes occasionally done when the water level drops or if debris starts building up
-Ammonia: 0ppm, Nitrite: 0ppm, Nitrate: 0ppm, pH: 6.5 (driftwood and tannin-rich leaves are used to keep the tank in a "black water" state)
Then there's also:
Experimental tank with a lone cherry barb that lives forever (1-gallon) :
-No lighting besides some indirect sunlight because of tank placement
-No filter or heater (temp. never drops below 70)
-Plants: Java ferns
-Substrate: River stones
-Started off as an experimental tank years ago. There's still a cherry barb alive so I just leave it as it is. This is a strange aquarium that doesn't require maintenance besides occasional feeding.
-50% water change once a year after summer to control algae (summer causes small algae blooms)
-Ammonia: 0ppm, Nitrite: 0ppm, Nitrate: 0ppm, pH: 6.7
As you can see, equipment/lighting/substrate don't always matter so much in the long run if appropriate plants are chosen
. I used to keep more high-maintenance planted aquariums (the plants I have now are all hardy species). They were fun but I don't have the time/desire to maintain tanks like that anymore--so my current freshwater tanks are basically me being lazy
Oh, I forgot (stupid since the tank is literally in front of me), I also have a 2.5-gallon with a single anubias plant and a dwarf puffer. You might have noticed a pattern with my plant choices by now which can give you ideas