First, LabVIEW has internal functions for performing the measurements that you indicated. However; these are not peformed visually on the graph, they are array functions.
Second, on the Graph, if you open the palatte, you will find some cursor functions. These will also perform similar operations to what you are looking for, right on the graph.
Third, if you are looking for something that you cannot find in either place above, then what you need to do is convert the graph to a bitmap image, bring it into a LabVIEW front panel, and then perform your operations.