Ooh I can't read all 21 pages but I'd like to point out that the OED prefers realize to realise! They say that the English switched from -ize to -ise to copy French and the Americans are correct. But not for -yse, so it is analyse and not analyze. Americans made the opposite error.
In some cases (not centre, colour, but some others) the changes are because English spelling was not properly standardised until the 19th century.
I've lived in the USA over a decade and I'm used to it all now. A friend of mine was complaining that her child had picked up the construction "needs washed" which is regional dialect where they moved to. As in, "those jeans need washed," instead of "those jeans need to be washed." There are some fascinating regional dialects in the USA. Along with "needs washed," you get "yinz" for plural you and "crick" for creek. (It's Pittsburgh, and if you ever see an old video of Fred Rogers, he has the accent.)
Some of the things, interestingly, have parallels in Spanish. In Spain, you have un móvil, in Latin America you have un celúlar. Loads of different slang, even some different grammar.
Also, soda is primarily the Northeast, the Great Lakes are pop, and down South it's all Coke. "Soda" is a catergory like "soft drink".