Dear Martin,
If i understood your requirement then you will get all the information referred below.
In the user decision step go to control tab.
Go for binding in the control tab.
In the right hand side you can system variable. In that Expand the BOR (_WORKITEM) .
In this you will find all the system variables related to Work item. (Who executed, who forwarded, when completed etc)
Create local container in the work flow and map required variables from User decision step to workflow by this way u will get the values in workflow then you can use it further in mail sending step also approved/rejected/forwarded on this date.
Below screen shot for your reference.
Thanks,
Anand