HI
you have set the GUID value properly. To set the values of Actual Revenue field you need to modify your Query String as given below.
var url = serverUrl + '/SFA/opps/dlg_closeopp.aspx?pID=' + guid + '&estimatedVal=' + crmForm.all.estimatedvalue.DataValue
It fills the value of Actual Revenue in the new window.
I'm sure this is too late for you, but I found that I also needed to add a "pType" argument ('&pType=3') to get the estimatedVal to show up. Also, I had an issue still where the status of the opportunity would not actually close when the close dialog
was brought up this way. I ended up having to write a workflow that would trigger on the field that I have triggering this dialog to show, and then close the opportunity.
Alessandro Graps