Greetings Craig:
Congrats on getting your pond structure completed. As with many hobbies, there's more than 1 method to achieve similar goals. Ultimately a system must be able to find its balance (w/the care-taker's assistance of course). This balance comes in the combination of plants, fish, waste load all of which boils down to the water quality.
It's possible to get a system going w/o pumps & filtration but there are trade-offs as there would be even w/extensive pumps & filters. I often refer to a giant urns where a few goldfish, submerged aquatics & a water lily would grow ... the water stayed clear but the system had to be replensihed by partial water changes (manual labor).
All systems can work & it's basically a trade-off of how much labor may be involved in getting it to work.
I'm personally a proponent of both skimming action as well as bottom suction in a water garden. Water (both outdoors & indoors) act as a magnet for dust, debris, seeds, pollen, leaves, twigs, gum wrappers, etc. This is esp. the case when outdoors & the collection can create a "skin" effect on the water surface when there's little to no turbulence. This debris (once waterlogged) will also sink to the bottom. In systems w/o pumps, etc. this would eventually mean you'd need to have a routine "pond vacuuming" or a full drain & clean-out.
Because of this, even in a small water garden/water feature, I like the benefits of both a skimmer & if not a bottom drain, a solids-handling submersible pump in which all the water would go to an external filter. The following layout would work well especially in your formal design.
I think having both pump & filtration is especially important in areas prone for high heat, sun & wind factor.
