Sega didn't really layout any established lore when Sonic was being marketed to the Western audience other than "cooler than the other guys". Outside of the "Sonic Bible" that was used in the Europeans comics and the initial American tie-in comic, SoA effectively just licensed out the name out the name and allowed all the creators to go nuts. This resulted in the "Loony Tunes"-tier AoStH
, the more edgy SatAM, and the Archie comics (That were basically SatAM in the style of AoStH
, but became their own form of autism as time went on). In fact, Sega didn't really take notice of (Or care about) what direction the Archie comics went until 2006 when one of their staff happened across the recent issue 155, the one with Sonic crying on the cover. Immediately they reigned things end and tried to get a handle on the comic's direction. The Penders let his autism lawsuit loose a few years later and the comics continued going to shit despite the writers doing everything to fix what had been happening.
At least that's the short version of the comics history. In regards to how robotization works, basically the organic parts of the body are literally turned into that of a machine, and I cannot say that in a better way. In regards to Bunny Rabbot, what happened was the Sonic interrupted the process halfway through, and that's why she's the way she is.