The impression I get from the 3e material is that the Warforged as we know them were a Cannith invention – otherwise you wouldn't have had precursor versions like the Warforged Titan. But this invention incorporated elements found in Xen'drik which Cannith artificers didn't fully understand, and which explains many "undocumented features" of the Warforged such as the ghulra (the unique symbols on their foreheads), free will, and having gender despite being sexless.
Yes and no, it depends on which section of which book you look at. It's not uncommon for the same book to have multiple versions in different (sub)chapters & (sub)sections.
That is not dead which can eternal lie,
It's more a matter of nuance. It's not like Cannith found a fully functioning creation forge down in Xen'drik and used it to start churning out Warforged. They* found something there that had been used to make something similar to Warforged and used it to bootstrap their own R&D, without fully understanding all aspects of it. I see it as akin to the situation in Terminator 2 (minus the time travel aspect), where Cyberdyne Systems had acquired a chip from the T-800 sent back to kill Sarah Connor, and were working on reverse-engineering the tech. They couldn't just take that chip and make Skynet right away, they had to figure out what the heck it was and what it was doing first.
Planned obsolescence, the bane of my existence. (What do you mean "you no longer support that model of printer"? It works perfectly fine, if you'd keep making ink cartridges for it! Grumble grumble grumble....)
In D&D, you can, it's just it requires a lot of magic. Presumably given Warforged are created with magic, and have some a "organic" components (not a term that means much, admittedly - it could just mean certain chemical structures - indeed contextually that seems quite plausible) some magic would also be needed to long-term maintain Warforged, but probably far, far less dramatic magic than with a conventionally alive being. It's also more likely Warforged could have some simple "procedural" way to to keep going. Like a "maintenance forge" or something (presumably a creation forge could do this). But if they lost access to those maintenance methods, presumably they'd eventually get so broken as to be basically non-functional, or have to change to some highly... alternative... methods which could get kind of exciting in sort of Promethean way.
This is a common thing in modern military procurement too - very contrary to in the 20th century, increasing numbers of machines used by modern Western militaries (or generally developed in the West) are designed to have short lifetimes before they require significant parts replacement, and those parts can only be replaced not by military-employed engineers, but civilian contractors who the companies who make the parts extremely expensively contract out to the militaries who bought their vehicles, weapons, etc.
