Help: Dynamic Stock Chart and Range Calculations

Hope everyone is well. I turn to your expertise for assistance with the following two items - any and all help will be greatly appreciated.

I'm trying to create a dynamic stock chart that returns only the 120 most current values in column(D). D1 is the header, and D2:D6 are empty due to adjacent data-sensitive formulas. Data formally begins at D7 and ends at D759. The desired chart series would initially be D:640,D:759. What would be the necessary steps / formula to create a dynamic chart that would continue to 'roll' as new daily-data is entered?

Finally, using the same data range requirements, how would I have H2 for instance, continually calculate the Average of this dynamic series?

The attached file contains all the above information, and any I may have omitted. Thanks for your time and any help.

-Chris