I'm just gonna number my responses to your points since I'm not really good at using the whole quoting system on this site.
1) I honestly wouldn't read too much into the images of the great spirit robot because as we have easily seen between the various artist styles and particularly with the artist during 06-08, there can be large discrepancies in the artwork. I would most go based on the GCI images of the robot and that one concept piece that you used for your map, since several people on a team worked to design how it looked, and not just one artist.
2) On the note of Greg accidentally cannonizing that the SC was in the pelvis doesn't make sense to me. We all know that Greg has made errors in his books before which he came onto this site to clarify. Unfortunately in the case of the Toa of Plant Life though for some reason he had to stick with them being male since he had a typo in a book. My point is though, if he accidentally cannonized something, that shows that he didn't mean to, and his intent is what we should take into consideration, the line of thought behind it.
3) As for the legs, yeah I know, it's something that's been nagging me. I made this map long before we had the really nice easy to see robot from Faber, and so I thought that there was more room in the hips for a dome that could contain those four islands. I've considered making the hip really only a junction where the tunnels going through the stomach tubes of the robot split off to go down each leg, but of course this would require a lot of work in photoshop to correct it, and it's not really something that I want to do right now.
4) And once again with the chest dome, yeah it's something that's been nagging me. My first attempt at a map I tried to make each island and continent in a dome, but I was nowhere near as successful as you and it looked like a garbled mess. Trying to put the SC in it's own dome really doesn't work because of the location of the NC and especially the pan handle that juts out from it. If I shrink down the SC then it might work, but at this point I kinda like having all the extra ocean space that is provided by having one whole dome, plus I'm not really too worried about structural integrity and the physics of it because I figure the GBs could find a way to make it work. I mean the domes probably aren't that tall compared to the rest of the robot, so they probably don't comprise the structure much. Phones and a lot of other things are hollow on the inside but they still manage to stay intact, so not something I've thought about much, you do have a point though.
5) I don't understand what you're saying about Zakaz, it's supposed to be near the throat which is Karzanhi to keep people from getting to the realm, this is something that Greg strongly hinted at in the old answers topic when people asked about it. He basically answered something along the line of, Zakaz was made so hostile for the purpose of keeping things away from that region, which makes sense to me. But I also know that Spiriah supposedly messed up and didn't mean to make the Skakdi so hostile and destroy Zakaz, so I don't know...
But also with Pridak's quote, I wouldn't think too much into it, he could have just said that because Xia is one of the best know islands, he could have said the northern continent too.
6) Yeah about the amount of area allocated between the domes and the edge of the robot shell, I know. That's another thing that's been nagging me but if I added more room or shrunk the domes a bit it would mess up the resolution of everything. Also actually, you know those tubes that run along the robot's shoulders, that would essentially fulfill the same role as the trapezius muscle, those actually have a gap between them and the robot's chest, so that would actually cut down even more on that area, so if I overlay the robot's exterior over the domes, part of the NC and Xia are actually not inside the robot. This is a bigger pain in the rear end to deal with though because I would need to reconfigure most of the central dome.
7) As for the islands in the hands, this is something that I considered and originally had them in the forearm as well, but looked at the official map, you'll notice that Tren Krom's island is more to the right of the other islands in the chain so that it doesn't line up with them. I always thought this was a way of showing that it was in the hand, and that in this image the hand was sorta curled in towards the body. Plus it would make sense why his island was never found since it was so much further away from the next to last island in the chain, the domes for the hands should definitely be smaller thought to allow more room.
8) On Karzahni, I thought that Greg had stated that it was definitely in the neck. Yeah I know that it was states to have a peninsula jutting out into the Metru Nui dome, and I originally did have it like that, but it got cut out when I changed the domes, so that's probably something that I could easily change in a matter of minute by just rotating the layer a bit. My one problem, is that the top point of the island isn't centered and is off to the left, so I would have to rotate it, but that's not that big of a deal if it's the only way it works.
9) On ignoring the canon details. The way I always think about it, is that Greg always said he thinks in words and not pictures, so we can move things around a bit to make more sense of his words, and when you have an entire team of people working on this project there are bound to be discrepancies, so I don't really view it as ignoring cannon facts, but more of just trying to sort everything out and make the most sense of all the information that we have.
10) I'm not sure where, but I could have sworn that Greg has said that KD is in the robot's chest. Honestly, I really would count the official map as the least cannon, as backwards thinking as that sounds. We have so many better pieces of art that seem to do a better job. I also made a threat with an entire theory about this a long time ago.
Basically the theory was that the codrex would sometimes need to blow off energy, which it did by shooting straight through the robot. The energy would go straight up and through Voya Nui and mount valmai, which is why it's there, and then the hole that we see the Mask of Life come out of. When the robot crashed a massive burst of energy was expelled and it blasted the entire region of Voya Nui out of the hole which was opened, which explains why the surface of Voya Nui managed to not get very destroyed, and why Voya Nui itself rocketed out of the robot.
Basically though, this is further evidence to support the position of the continent, although your theory works too. Also I would like to point out that we already know that the size of Voya Nui on the official map is way too big, so right there off the bat we know that there are inaccuracies about the map. My idea is that when that map was made, the SC was intended to be in the gut region of the robot, but it hadn't been planned that that region would be hollow at this point.