You'll want to go into Format > Paragraph and you can change the spacing
between letters and between lines. I'm assuming that is what mean (It's been
so long since I've used a typewriter, I can't remember exactly what the pitch
is )
Whether text has a fixed or variable pitch is determined by the font
you apply to it. "Proportional" fonts have variable pitch, and
"nonproportional" ones have fixed pitch.
There are only a few common nonproportional fonts in Windows: Courier
New and Lucida Sans Typewriter are the usual suspects.
For both of those fonts, it's convenient to remember that the point
size multiplied by the pitch (characters per inch) is 120 at all
reasonable sizes. In other words, 10 pt text will be 12-pitch, and 12
pt text will be 10-pitch.
For proportional fonts, about the only control available is in
Format>Font>Character Spacing where you can Expand or Condense the text. How
effective this is for your requirements may be questionable.