The th would not have been smaller. You had to roll the paten (carriage) to superscript, but it did not make the letters smaller,just raised where you were able to slide the paten.
The line pattern could not have been replicated on Word, as it has been shown to be many times over by many different experts/bloggers, etc.
Again, I am fairly convinced that these docs were forged. All I need to do is look at the source BUT the Executive was perfectly capable of typing a superscript if ordered with that key. No rolling of the platen would be necessary.
Regarding the line spacing, that is suspect. I doubt that the typewriter would have identical line spacing compared to the word processed version. Still, I think that other indicators of forgery are stronger then the typography..