如何调整宏中COUNTIF/SUMIF公式以动态引用整列数据？

我正在为团队制作一款行项目运费重算工具，已基本完成，希望添加数据汇总功能减少手动操作。刚接触VBA，目前依赖宏录制生成代码后修改，暂无法用VBA创建数据透视表，因此使用了SUMIF和COUNTIF公式。当前公式仅适配固定行数（测试数据为64行），但数据行数会随运单数量变化，列标题固定。我不想用超大行数引用担心影响性能，希望调整公式以动态引用整列；同时也希望了解更简洁的动态实现方案。

现有宏代码如下：

Sub TestTable()
'
' TestTable Macro
'
' Keyboard Shortcut: Ctrl+t


'Summary Sheet

'Naming Summary Columns
Worksheets("Summary").Select
    Range("B3").Select
    ActiveCell.FormulaR1C1 = "Mail Class"
    Range("C3").Select
    ActiveCell.FormulaR1C1 = "Count of Postage"
    Range("D3").Select
    ActiveCell.FormulaR1C1 = "Sum of Postage"
    Range("E3").Select
    ActiveCell.FormulaR1C1 = "Sum of Rerate"
    Range("F3").Select
    ActiveCell.FormulaR1C1 = "Sum of Difference"


'List unique Mail Classes
Worksheets("Summary").Select
    Range("B4").Select
    ActiveCell.FormulaR1C1 = _
        "Ground Advantage"
    Range("B5").Select
    ActiveCell.FormulaR1C1 = _
        "Priority"
'Count Unique Mail Classes
    Range("C4").Select
    ActiveCell.FormulaR1C1 = _
        "=COUNTIF('Test Sheet'!R3C1:R64C1,""Ground Advantage"")"
    Range("C5").Select
    ActiveCell.FormulaR1C1 = "=COUNTIF('Test Sheet'!R3C1:R64C1,""Priority"")"
    Range("C3").Select
' Sum of Postage
    Range("D4").Select
    ActiveCell.FormulaR1C1 = _
        "=SUMIF('Test Sheet'!R3C1:R64C1,""Ground Advantage"",'Test Sheet'!R3C4:R64C4)"
    Range("D5").Select
    ActiveCell.FormulaR1C1 = _
        "=SUMIF('Test Sheet'!R3C1:R64C1,""Priority"",'Test Sheet'!R3C4:R64C4)"
'Sum of Rerate
    Range("E4").Select
    ActiveCell.FormulaR1C1 = _
        "=SUMIF('Test Sheet'!R3C1:R64C1,""Ground Advantage"",'Test Sheet'!R3C5:R64C5)"
    Range("E5").Select
    ActiveCell.FormulaR1C1 = _
        "=SUMIF('Test Sheet'!R3C1:R64C1,""Priority"",'Test Sheet'!R3C5:R64C5)"
'Sum of Difference
    Range("F4").Select
    ActiveCell.FormulaR1C1 = _
        "=SUMIF('Test Sheet'!R3C1:R64C1,""Ground Advantage"",'Test Sheet'!R3C6:R64C6)"
    Range("F5").Select
    ActiveCell.FormulaR1C1 = _
        "=SUMIF('Test Sheet'!R3C1:R64C1,""Priority"",'Test Sheet'!R3C6:R64C6)"
'Column Totals

    Range("C6").Select
    ActiveCell.FormulaR1C1 = _
        "=SUM('Summary'!R4C3:R5C3)"
    Range("D6").Select
    ActiveCell.FormulaR1C1 = _
        "=SUM('Summary'!R4C4:R5C4)"
    Range("E6").Select
    ActiveCell.FormulaR1C1 = _
        "=SUM('Summary'!R4C5:R5C5)"
    Range("F6").Select
    ActiveCell.FormulaR1C1 = _
        "=SUM('Summary'!R4C6:R5C6)"
    Range("G6").Select
    ActiveCell.FormulaR1C1 = _
        "Grand Total"
'Formatting Cells and Data type
    Cells.Select
    Cells.EntireColumn.AutoFit
    Range("D4:F6").Select
    Selection.Style = "Currency"
    Range("C3").Select
End Sub

注：“Column Totals”部分为静态汇总输出，无需修改。

内容的提问来源于stack exchange，提问作者Paulonious1