There are a number of ways to do it, but I make fractions using Dan Rodney's excellent (and free) Proper Fraction script. After it's installed; assign it a keyboard shortcut. Then type your numerator/denominator, select it, and invoke the script. With just a couple keystrokes, you've got a perfectly formatted fraction.
As for the PDF tables, I'd try exporting the host file to RTF and copy/pasting from there. In case you're unaware, to paste values into InDesign table cells, the number of (pre-existing), cells/rows/columns in InDesign must match those copied (from) exactly, and must be pre-selected when the Paste command is executed. So...
1. Set up empty destination table in InDesign which matches the source structure.
2. Select source cells and Copy.
3. In Indesign, select exact same (x, y, qty), range of destination cells and Paste.
How do I create a style (or whatever) that will allow me to just type in the numbers and have them automatically apply small formatting to the fraction portion of the number whenever it sees a "/"?
Create a character style (Open Type) include with fraction.
In pragraph style create a grep style:
Apply style: select character style.
To Text: \d/\d
Thank you both for the excellent help. Just the info I was looking for. Much appreciated!!