huh... I actually read that whole thing (had to set text size to largest though)
you make some excellent points and of course saying Bush=Hitler is complete and utter nonsense. The only valid comparison you can make is that between some policies. But that leads to another debate namely the "This is bad because the Nazis also did it" debate. This is because many people can't bear that even somebody completely evil can do something smart and beneficial. While I do not consider it alright to do something good with an evil intent (old example: "Hitler build the "Autobahn") I do not consider it wrong to repeat the same thing with a good intent.
There are indeed historical parallels between today's US and 1930ies Germany but they don't come from fascism but from being a major military power. There are some signs of authoritarian government and media control but as long as they are not "fascist" or "nazi" they should not be called that but simple "authoritarian tendencies" even if it's less catchy
After all that I also want to say that IMHO it's a lot smarter to wear one of those stupid T-Shirts than to seriously argue why Bush=Hitler. The first is making thoughtless use of a very stupid symbolism the second is actually believing that kind of nonsense and therefore trying to prove it.