Find percentage IF number present

I have a few of questions re: Table_Solid:

1 - presumably "Present" just means there is match of AP No. (Col A) and Header (C:E) ... ?

2 - is % at Surface meant to be the count of A at header divided by total count of header ?

3 - Your headers don't seem to tie out completely to any given column on the source sheet... am I missing something ?
eg for D1 you would need to add [Undifferentiated], no ? ... and E1 would need to change significantly...

If you can answer the above I'll endeavour to provide a solution.