Hi shyamigcar2,
Not sure about 2) and 3), but to change the scatter plot to a Line+Symbol plot for 1), you can run the commands like: range rg=[Graph3]2!1; //1st plot in 2nd layer in Graph3
layer -i202 rg; //202=Line+Symbol, 201=Scatter, 200=Line
Hope this helps you.
--Hideo Fujii, OriginLab