How to plot pie chart(s) with click of button and set limits?

Hi,

A snap shot of this excel file. End of the day, I want to display the man hour for each task in the Pie Chart

I have a few issues here.. I want to
1) Plot the pie chart as shown in the file when i click on a button. Is there a script for it beside me recording a marco? (with the chart name set as well)

2) Is there a way i can set the max limit to the pie chart? The max hour should be 40.. The way i am doing now is to pre-define the '40' and minus away those hours used.

3) If there are multiple entires for a same task, can the pie chart shows a combined value instant of showing two?

Thanks in advance.