For the second part of your question you could use a helper
column (say column G) with the numbers 1 to 20 or whatever
descending down the column.

Your formula will then be
=SUMPRODUCT(--('All History'!$B$2:$B$2000=$G1)

As you copy down the $G1 reference will update to $G2, $G3 etc.

HTH
Martin