Well, if it were me, I'd scrap the list. Fishin4cars got you well grounded in liner sizing, which is a good start.
Shelves: I'd discourage them. I'm currently removing mine in my 3000g. A better idea would be to have straight walled sides, with a sloping bottom, either to the center (say, from 2' deep at edge to 4' deep at center) or to one end (again, from 2' to 4' deep). Shelves just provide an area for predators to access your pond. You can always put plants on milk crates a little off the edge.
At that deep point, I'd put a bottom drain. They're really easy to install when building a new pond. The bottom of your pond will develop a carpet of algae (not the green water kind, but good stuff) and fish crap (bad). With the sloped design, any water gravity will cause the fish crap to collect at the low point (where the bottom drain (BD) is, so it can be removed.
Okay, with that settled, save money on the underlayment and use old carpet (synthetic fibers, though, not wool or anything natural), make very certain the old staples are removed.
For lights, I'd use low voltage LEDs. They're brighter, use much less energy, and the bulbs will never burn out.
The waterfall foam: Use Great Stuff, from Lowes or HD. Less than half the cost, dries dull yellow, but here's the rub with that: if it's underwater, it'll develop carpet algae, too. If it is exposed to the air and sun, you'll have to paint either color of foam to defend it from long term UV damage, so just use the cheap version.
Filter: You could build a DIY filter easily for a tenth of that price, put a 9W UV in for around 60-75 bucks. Just use textured strapping for filter media, really cheap, check out the sticky threads in construction to see a few. My advice would be to invest, though, in real Matala pads for prefiltering the water before it goes into your biofilter. Fish poop is not really good for a biofilter.
Spiral nonkink tubing: PVC is a lot cheaper, and 2' flex PVC (available at any hardware) is excellent & can use standard PVC fittings, which will give you more options down the line.
Pump: Lots of people will have lots of opinions about pumps, and here's mine: My money is on external pumps. They last longer if cared for, they're crazy efficient, they keep high voltage electricity away from the water, just use a leaf basket and you never have to haul a clogged up pump out of the water to figure out what's wrong with it, you can look right at it. Advice is, for ease of use, mount it in a little pit below water level, inside a big tote with lid, you can cut your pipe entry and exit out of it, etc, and that will keep it protected from rain and out of sight.
To camoflage the back of your setup, use the dirt from digging the pond, or concrete blocks, or lattice, or shrubs. Whatever you want, just make sure you can easily get back there for maintenance.
Whew, lot of info, but wait and hear some other ideas, too, before starting. And, good luck! If you don't really get any of this, just ask. Welcome!
