Grid radio buttons are referenced like this: QuestionName_r# where # is the number that corresponds to the list index. If you wanted to reference the radio button selected for the first row of a question called Q14, the variable in the data of the respondents would be Q14_r1.
If you wanted to reference this value in, say, the header of another question, you could put it inside SSI Scripting tags like this:
Please tell me why you rated my brand [%Q14_r1%].
If you wanted to investigate the minimum and maximum values used along the scale, you could build a constructed list using the AddSorted() function. You could then reference which item is first and last, and also reference the value of the first and the last item. If you haven't done any constructed list building before, check out the help files at http://www.sawtoothsoftware.com/help/issues/ssiweb/online_help/index.html?hid_web_listbuilding.htm.