Converting Excel Formulas to DAX

Didn't have time to read the whole thread, but your WHB is impossible in DAX as you've got it defined. Luckily we can redefine it in a much more reasonable way (in terms of fields being accessed). Here are all the measures in clean DAX for you. It should be a good exercise in observing row vs filter context.

DAX isn't really the tool of choice for this, though. This sort of data munging should be done before the model is loaded. Unless you want these as measures, in which case, most of the ALL()s should be replaced with ALLSELECTED(), and the raw column references will have to be wrapped in SUM()s.

Steve = 
DIVIDE( SomeDamnTable[Fred], SomeDamnTable[Allen] ) // All row context

Sysco = 
DIVIDE(
	SomeDamnTable[Fred] + SomeDamnTable[X] // All row context
	,SomeDamnTable[Allen]
)

Mary = 
IF(
	SomeDamnTable[Fred] >= SomeDamnTable[Allen] // All row context
	,0
	,SomeDamnTable[Allen] - SomeDamnTable[Fred]
)

Impact = 
CALCULATE( // Do this whole thing in a filter context made up of the entire table
	DIVIDE(
		SUM( SomeDamnTable[Fred] )
		,SUM( SomeDamnTable[Allen] )
	)
	,ALL( SomeDamnTable )
) - DIVIDE(
		CALCULATE( // this CALCULATE is in a filter context of the entire table
			SUM( SomeDamnTable[Fred] )
			,ALL( SomeDamnTable )
		) + SomeDamnTable[Mary] // This is row context
		,CALCULATE( // this calculate is in the filter context of the whole table
			SUM( SomeDamnTable[Allen] )
			,ALL( SomeDamnTable )
		)
	)
		

Bob = 
IF( // all row context
	( SomeDamnTable[Fred] + SomeDamnTable[X] ) >= SomeDamnTable[Allen]
	,0
	,SomeDamnTable[Allen] - SomeDamnTable[Fred] - SomeDamnTable[X]
)

WHB = 
CALCULATE(
        DIVIDE(
                SUM( SomeDamnTable[Fred] )
                ,SUM( SomeDamnTable[Allen] )
        )
        ,ALL( SomeDamnTable )
) - CALCULATE(
        SUM( SomeDamnTable[Impact] )
        ,FILTER(
                ALL( SomeDamnTable )
                ,SomeDamnTable[Index] <= EARLIER( SomeDamnTable[Index] )
        )
 ) 

You should try to do this sort of thing before your data hits your model. Here's some Power Query to get you there. You can examine all this in the .pbix here.

let
    Source = Table.FromRows(Json.Document(Binary.Decompress(Binary.FromText("i45WMlTSAWMDMI7ViVYywhAxxhAxwRAxxRAxwxAxxxCxwBCxxBAxNIAKGSKEDFGFYgE=", BinaryEncoding.Base64), Compression.Deflate)), let _t = ((type text) meta [Serialized.Text = true]) in type table [Product = _t, Allen = _t, Fred = _t, X = _t]),
    #"Changed Type" = Table.TransformColumnTypes(Source,{{"Product", Int64.Type}, {"Allen", Int64.Type}, {"Fred", Int64.Type}, {"X", Int64.Type}}),
    Steve = Table.AddColumn(#"Changed Type", "Steve", each [Fred] / [Allen]),
    Sysco = Table.AddColumn(Steve, "Sysco", each ( [Fred] + [X] ) / [Allen]),
    Mary = Table.AddColumn(Sysco, "Mary", each if [Fred] >= [Allen]
then 0
else [Allen] - [Fred]),
    Impact = Table.AddColumn(Mary, "Impact", each ( List.Sum( Mary[Fred] ) / List.Sum( Mary[Allen] ) )
- ( ( List.Sum( Mary[Fred] ) + [Mary] )
  / List.Sum( Mary[Allen] ) )),
    Bob = Table.AddColumn(Impact, "Bob", each if ( [Fred] + [X] ) >= [Allen]
then 0
else [Allen] - [Fred] - [X]),
    Index = Table.AddIndexColumn(Bob, "Index", 1, 1),
    WHB = Table.AddColumn(Index, "WHB", each let
  CurrentRow = [Index]
  ,Base = 
    ( List.Sum( Index[Fred] ) 
      / List.Sum( Index[Allen] ) )
  ,SumImpact =
    List.Sum(
      Table.Column(
        Table.SelectRows( Index
          , each [Index] <= CurrentRow )
        ,"Impact" ) )
  ,WHB = Base - SumImpact
in
  WHB),
    #"Removed Columns" = Table.RemoveColumns(WHB,{"Index"}),
    #"Changed Type1" = Table.TransformColumnTypes(#"Removed Columns",{{"Impact", Currency.Type}, {"WHB", type number}, {"Mary", Int64.Type}, {"Sysco", Int64.Type}, {"Steve", Int64.Type}, {"X", Int64.Type}, {"Fred", Int64.Type}, {"Allen", Int64.Type}, {"Product", Int64.Type}, {"Bob", Int64.Type}})
in
    #"Changed Type1"