Non-Numeric Values in Appraisal Template

All,

I wanted to know if these are possible

1) How we can make the columns to accept the non-numeric characters. Currently it only accepts the numeric.

2) How can we make the columns blank - Current it always shows "0.0" - for eg.

Please see the screen shot here

http://img600.imageshack.us/img600/8420/appraisal.jpg

Aneez