So I've asked Ramon about the positioning of the numbers, and the reason for it is because its easier for the eye to "read" across all the digits if you put them all together like that, rather than in a single line or something. If you try the speed software, you'll see what I mean. In one second, you may not even be able to "read" across all the digits, so you'll find your self re-organizing the position of digits.
As for why some columns are 4 digits and some are 3, he's tried to explain it to me but I think something gets lost in translation. But what is clear is that he uses a number system at some point in the attempt. I believe he "looks" at the first two 3 digit columns (those are memorized by just looking at them, the next two 4-digit rows are translated into images. The last column is just "said" in mind at the last fraction of a second. Which is why he rights it down first so he doesn't forget it.
It's still amazing to me that he can do it all in 1 second. Back in September I trained for a few weeks because I was keen on going to the championship, and it was really fucking hard. It has a lot to do with speed reading skills as well. You need to be able to read quick and create associations as fast as you see the number.
Crazy stuff.