Kalle gives great advice
. Heed it. I only depart somewhat strongly from what he's told you in one specific item. And in another, I have a slight difference, just based on aesthetics - his suggestion is easier to execute successfully (no leaks). Perhaps I can supplement or repeat in different words, otherwise:
1. I'm looking at build guides and there seem to be various ways to separate the water section from the land including egg crate, this thick mesh called Matala, and various types of soft foam. I'm leaning toward a false bottom in the back out of egg crate and rocks/Great Stuff to conceal it - does Matala actually provide filtration? Are there any other suggestions? I have some Hygrolon.
Wow lots of questions and topics all jumbled in here. let me stick with separating land from water
. Kalle suggests glass and that works well and is easy to do. However it has two downsides in my view, 1) unless you modify it somehow, you look right through it into your "layer cake" of substrate, barrier, and drainage layer, and 2) if you're going for a naturalistic look, glass doesn't really do it. Not for me anyway. I started with glass, but came to be rather dissatisfied with it, aesthetically anyway. If you absolutely, positively want no leaks and maybe can't be bothered with all the work I describe below - go with a glass land/water separator.
But what I do instead of glass is create a "berm" of foam. Spray foam, foam board, or pieces of recycled packing foam, or some of each - hey, it really doesn't matter as long as you wind up with a single cohesive elongated unit. Then I coat the foam berm in epoxy, to waterproof it. Expect leaks, and take care to prevent them. I usually build my berm outside the viv. Wax paper is a good work surface, almost nothing (not spray foam, not epoxy, not construction adhesive) sticks to it. Once I'm done carving I epoxy the berm foam on all surfaces except those
that will touch the glass - those
I leave as bare foam, and on those I smear a full coat
of black, fish-safe, 100% silicone to affix the berm to the glass. I also lay a bead of silicone on the glass, all along the margins of the berm. That fills any gaps if I have failed to create perfect 90-degree angles on the berm ends, or don't have a perfectly flat bottom edge to the berm.
Between carving the foam and tinting the epoxy, you can - with some crafting skills - make it look a whole lot like natural rock. Note, anything under dirt needs no carving or tinting - it's gonna be buried. Something to remember too - nobody's born with any
skills, but anyone can develop them. Don't be intimidated, just get started.
Oh, this is out of order but I think it's helpful - I like to use a "permanent marker" to draw my layout on the glass. Rubbing alcohol cuts that stuff like a charm, any time you want to remove it. You can trace your layout onto your wax paper with the same permanent marker. Just let the ink dry on the paper before touching it, otherwise it'll smear.
Kalle mentioned drilling & bulkheading in two places - under or behind the land, and under or behind the water. YES!!! TWO BULKHEADS!!!
I like behind more than under, as it's awkward to have something sticking out the bottom of a glass viv. Sooner or later, you are sure as shit to break that bottom pane of glass by whacking the bulkhead against something. It's much easier to avoid doing that if the bulkhead is on the rear (or side, or front, if need be) of the viv. Trust me on this.
2. How do I control water level when I have a misting system running multiple times a day? Do I need to cut a hole in the tank and install a bulkhead?
The bulkhead on your water side (more detail below) establishes your "control elevation". Just drill your hole as far up the back, as you want your water to be deep.
3. Do I just need a pump for the waterfall feature, or do I need some sort of filtration system? How do I clean and control the water quality? I'll start with just plants in the tank, but probably want some type of semi-aquatic animal or fish eventually.
Now, where I depart somewhat strongly from Kalle's advice is on draining both areas into "a" (single) sump. I prefer to drain my water area
into a recirculated (pumped, and sometimes filtered) sump, and to drain my substrate area
into a throw-away vessel (sized from a yogurt or margarine container to a bucket, depending on viv size). The issue is water quality - tannins, salts, fertilizers, what have you. I just prefer to keep that stuff out of my water feature, and have an easier job of managing the quality of my recirc water. The only "right" answer is what's right for your plants and animals, and for you.
Note that depending on how much misting and maybe hand-watering you do, and how strongly your substrate-mounted plants act as water pumps, and especially how much splashing your water feature does into your substrate layer (I like adjustable pumps, so you can dial them back to the pioint you get no splashing) the frequency with which you'll need to dump your throw-away water will vary. It could even vary seasonally, if you have humid and dry seasons where you live. Regardless, make it a habit to check that bucket! Otherwise, you may find it has overflowed...and normally the water in it looks more like tea, than pure water. Nasty on a carpet.
On the water-area side, and its sump - I'd say for now ("just plants") you could run just the pump. Later, if you get animals, you can add filtration. The easiest way would be to just run an external canister filter that both pulls from and dumps into that sump of yours. But you can do any number of things. You can hide all this sump, bucket, canister filter crap in a stand-cabinet if you like. My herp room is kind of industrial, everything is out in the open, I don't have ANY "display tanks" - it's all up to your tastes. And those of your spouse, partner, or roommates.
In closing, I'd say you - and I, and all the rest of us! - must balance the desire - truly, the wisdom - of doing lots of research before you even start, with the practical heuristic value of just getting started, wherein you'll make plenty of mistakes, develop many opinions and preferences, and gain loads of actual first-hand experience. I perceive - rightly or wrongly - that you are inclined towards careful, deliberate, studied activity. Those are good attributes, good habits. Just don't wait too long - life is short, time flies, situations change. Usually, you get busier with things that deny you the time to craft vivs. So don't fritter away the free time you have right now - get building! Just about any mistake can be corrected or mitigated, or just tolerated. Good enough IS good enough, and perfect is always a pain in the ass, and rarely worth the trouble.
OK, old guy rant over. Ha ha ha. Good luck!