I am having some difficulty in determining how best to create a
workbook.

First, it will contain a tab/worksheet for each month/year. Each
worksheet contains a production schedule with target and actual dates
for each source file scheduled for that month. Some source files are
scheduled for weekly or daily receipt so could be recurring during a
single month.

Secondly, I need to create a summary worksheet where I can populate it
based on a selection from a dropdown box of each available worksheet/
month. I've got the dropdown box being populated just now need to
figure out how to reference that to populate the summary worksheet.

Any ideas?

Now for some of my recurring files, I may have a need to only
represent the most recent date on the summary worksheet so how would I
manage to identify the most recent date and pull that into the
summary?

I know this isn't described very well so let me know if I can clarify
anything.