Save and load WPF Chart Plot

Hi

I am using OxyPlot to make chart, it could add annotations to chart.
Q1: One question is what is the general way to save all data in the plot so that could be open in future?

There is an example, WPF DrawTools, which create property class for each kind of shape.
And serialize property classes. Then use them to rebuild drawing later.

Q2:Is that a good way to save data?
It need to make an separated property class for each shape, that seems duplicate works.

Q3: If property class is good way, how about include property class in each shape class?

Thanks