Michael-
On Sugar- Sugar is much too valuable to add to the soil. Better to use it to make fuel alcohol, which is something else I've been working on.
On Temperature- I think that low temperatures are best for ADE charcoal as it then retains more of the plant resins that are used in binding the nitrogen.
On Nematodes- Yes, I'd like to read the "Quirky Science Fact." Beneficial nematodes are an important part of healthy organic soils and I'm sure are found in abundance in Terra Preta.
On Charcoal- I don't see why coconut charcoal wouldn't work just fine if you can get it cheap enough. One of the questions I have about the Amazonian charcoal if whether it's made from hardwoods, and whether the resulting resins might be different in various materials. I've read that alder is the preferred wood for making charcoal for use in forges, followed by mountain ash, and oak, but I don't know how that would relate to what we are doing here.
Coal is NOT the same as charcoal. Not only does it contain various percentages of sulfur and other chemicals, but it also has a lot of flammable volatiles, which is what helps it to burn. Coal is made when anaerobic pete bogs are subducted and put under heat and pressure for a few millenia. Coal is around 90% carbon, with the rest made up by the other chemicals. Probably not at all good to put in your garden soil. When the volatiles are removed, the resulting product is called "coke," and it burns cleaner than coal but needs a strong bellows to keep it going.
Regular charcoal briquettes are not a good substitute for ADE charcoal either. They are made from a combination of sawdust charcoal and coal, and sometimes petroleum coke, which can be high in heavy metals. Most of the volatiles and other chemicals actually burn away before you start cooking, but they would still be present if you ground them up and put them in your garden. Kingsford charcoal briquettes are made from: powdered charcoal, anthracite coal, limestone, starch (as a binder), sawdust, and sodium nitrate and a few other ingredients. I've just heard recently, however, that WalMart and Home Depot here in the US both carry what is called "Lump Charcoal," which is the pure stuff, no additives, and it is available in various kinds of wood: hickory, mesquite, oak, etc. You can find a bunch of other brands online as well. A little too expensive to suit me.
On Clays and Kitty Litter- I'm not sure about the kind of kitty litter you get, but my experience is that the stuff is simply made from dry clay, not kiln fired. When it gets wet, after a while it just turns back into sticky clay, which would not be good for a garden unless you need to slow down your drainage. I thought I'd check with my local nurseries to see if they have any broken terra cota flowerpots they'd like to get rid of.
I had already read that same paper about the mineral composition of the ADE pottery that you posted, but I don't know enough about pottery to see how this compares to terra cota. Some of the pictures I've seen of it though, looks just like it. That's what I'm going to use.
On Water- I just made up a batch of home-made Terra Preta and the very first thing I noticed is that it holds a heck of a lot of water when you get it wet. It took a little time before the water started soaking in, but the stuff holds it like a sponge. I've set a wet pot of it out in the sun to see how long it takes to dry out compared to my regular compost. I think it's going to be really good for water conservation.
Here's a pic of the stuff I made:
