How to use GROUPING function in SQL common table expression - CTE

I have the below T-SQL CTE code where i'm trying to do some row grouping on four columns i.e Product, ItemClassification, Name & Number.

;WITH CTE_FieldData
AS (
    SELECT 
      CASE(GROUPING(M.CodeName))
            WHEN 0 THEN M.CodeName
            WHEN 1 THEN 'Total'
            END AS Product,

        CASE(GROUPING(KK.ItemClassification))
            WHEN 0 THEN KK.[ItemClassification]
            WHEN 1 THEN 'N/A'
            END AS [ItemClassification],

        CASE(GROUPING(C.[Name]))
            WHEN 0 THEN ''
            WHEN 1 THEN 'Category - '+ '('+ItemClassification+')'
            END AS [Name],

            CASE(GROUPING(PYO.Number))
            WHEN 0 THEN PYO.Number
            WHEN 1 THEN '0'
            END AS [Number],

        ISNULL(C.[Name],'') AS ItemCode,
        MAX(ISNULL(PYO.Unit, '')) AS Unit,
        MAX(ISNULL(BT.TypeName, '')) AS [Water Type],
        MAX(ISNULL(PYO.OrderTime, '')) AS OrderTime,
        MAX(ISNULL(BUA.Event, '')) AS Event,
        MAX(ISNULL(PYO.Remarks, '')) AS Remarks,
        GROUPING(M.CodeName) AS ProductGrouping,
        GROUPING(KK.ItemClassification) AS CategoryGrouping,
        GROUPING(C.[Name]) AS ItemGrouping
    FROM CTable C INNER JOIN CTableProducts CM ON C.Id = CM.Id
                INNER JOIN MyData R ON R.PId = CM.PId 
                INNER JOIN MyDataDetails PYO ON PYO.CId = C.CId AND PYO.ReportId = R.ReportId
                INNER JOIN ItemCategory KK ON C.KId = KK.KId
                INNER JOIN Product M ON R.ProductId = M.ProductId
                INNER JOIN WaterType BT ON PYO.WId = BT.WId
                INNER JOIN WaterUnit BUA ON PYO.WUId = BUA.WUId
                WHERE R.ReportId = 4360
    GROUP BY M.CodeName, KK.ItemClassification, C.Name, PYO.Number
    WITH ROLLUP
)
SELECT 
    Product, 
    [Name] AS Category,
    Number, 
    Unit as ItemCode, 
    [Water Type], 
    OrderTime, 
    [Event], 
    [Comment]
    FROM CTE_FieldData

Below are the issues/problems with the data being returned by the script above and they are the ones i'm trying to fix.

1. At the end of each ItemClassification grouping, i extra record is being added yet it does not exist in the table. (See line number 4 & 10 in the sample query results screenshot attached).

2. I want the ItemClassification grouping in column 2 to be at the beginning of the group not at the end of the group. That way, ItemClassification "Category- (One)" would be at line 1 not the current line 5. Also ItemClassification "Category- (Two)" would be at line 5 not the current line 11

3. Where the "ItemClassification" is displaying i would like to have columns (Number, ItemCode, [Water Type], [OrderTime], [Event], [Comment]) display null. In the attached sample query results screenshot, those would be rows 11 & 5

4. The last row (13) is also unwanted.

I'm trying to understand SQL CTE and the GROUPING function but i'm not getting things right.