The paging is a simple process. You click the next page button and the next <page_size> number of records are set as the ItemsSource of the GridView. It does not know about columns, rows and so on. Everything happens through the IPagedCollectionView interface. You can find details about the features of the DataPager in our documentation.
Although there is not an option to automatically control the page size based on the available space, you could calculate this space yourself and initially assign the appropriate PageSize based on the different resolutions.
I am not sure what do you mean by "to track and control the RadGridView's current top-shown records", would you please clarify?
the Telerik team