So, first of all, i want to mention how insanely lucky you are to have a postmodern lit class in high school! If I had something like that, I'd have felt differently about english going into university, nevertheless it's become my major and i couldn't be happier! : )
I don't have all the answers for this because I'm a little rusty with my facts, but the reason I think that the Second Eric Sanderson gets that name is because this is the first occasion that he completely lost his memory. I figured that the past occurrences left him with gaps in his identity, but this was the first time he ended up more or less as a blank slate.
As for the Shotai-Mu, I don't know. I should probably look over the book sometime soon!
Gavin the Cat, though, is an anomaly. He's mentioned in quite a few posts on here, so i suggest the search button to browse through some theories. But (don't take my word on this) I'm pretty sure that we'll see more of Gavin in the future. Somehow/someway.
This is a theory i find intriguing, comparing Eric/TheSecondEricSanderson with Ian/Gavin
thethird wrote:
These concepts, in the most rudimentary sense, are intrinsic to the thought experiment “Schrodinger’s Cat”. This quantum physics experiment demonstrates the principle of superposition: any object (in this case a cat in a sealed chamber) is actually in all possible states simultaneously (i.e. both dead AND alive in the chamber), as long as no one checks its status. It is the observation itself that causes the object to have a single state (dead OR alive). Tegmark (!) developed the experiment further, _taking the view of the cat_. Is Ian in fact Schrodinger’s conceptual cat?? As such, Ian symbolizes the possibility of multiple states of being (states of mind?) and permits both fates of Eric (Incidentally, Ian himself has a ‘twin’ in the unseen Gavin.).
from this thread:
http://forums.steven-hall.org/yaf_postst47p5_The-ending-merged-threads.aspxI'm sure others can give better answers than I can! Hope this helps, and keep up your interest!