The book I'm typesetting right now has numerous fractions, and I was wondering if I could get advice on the best way to create them. I don't have Elements of Typographic Style handy at the moment.

1. I know enough to use the fraction-slash (I forget the correct name)

2. What percentage of the full point size can I make the numerator and denominator without them looking too light?

3. Should it be flush with the baseline, or can lowercase numerals (like 3) hang below?

Paul