Is it possible to change text size & formatting of Numbers' formula input field?
When I click in the formula entry bar I get an additional toolbar that has a "Formula Text Size" field. Does this appear on your screen?



Here's a screenshot from the Numbers '09 User's Guide:



I haven't found a way to make it larger than 14.

Edit

I figured out how to make it larger than 14.


Quit Numbers
Run Terminal
Type the following command:


defaults write com.apple.iWork.Numbers LSFormulaBarFontSize 80

When you run Numbers again your formula bar is plenty big:



You can use a number smaller than 80 in the Terminal command for a more reasonably-sized formula bar.