Help with multiple COUNIFS & SUMIFS

Context:
I'm putting together a flexible template to combine samples into pools of various sizes and check that the pools fulfil certain criteria.



Problem:
I need to
Find the first instance of a pool number (in col. D)
Count the number of cells with the same pool number (in col. D) and display on the row of the first instance
Count the values in C divided by sum values in G for the cells that have the same value in D.
Max G/Min G for the cells that have the same value in D (in J).
Create a highlight/marked cell in K (for user data entry) for rows that have the first instance of a pool number in D
Value in G* value in J for rows that have the first instance of a pool number in D
Sum of M for rows that have the first instance of a pool number in D
Average of C for rows that have the first instance of a pool number in D


I started trying to build something flexible and got stuck so the spreadsheet is a bit of a mess.


Thank you in advance for any help you might be able to offer.