I am glad to see that you were able to find solution for some of the issues.
Now for you current question, regarding the Master/Content page scenario: in a complex scenario like WebUserControls or Master/ContentPages you should use RadAjaxManager in the Master page and RadAjaxManagerProxy in the Content page. Please refer to the following help article: "RadAjaxManagerProxy
Furthermore for your scenario I may suggest that you fire an AJAX request within the "refreshGrid" function with RadGrid as initiator (the RadGrid must be set as AJAX initiator and as "UpdatedControl" in the RadAjaxManagerProxy as well). More information could be found at this help article
Another important thing that should be pointed out is that you need to move the following line from the "ItemCommand" server-side event to the "Page_Load" event in order to overcome ViewState errors that will occur:
Hope that helps.
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