If the row ranges are predefined, I would rather use named ranges in the spreadsheet and refer the named range in the excel source; instead of reading entire sheet and...

Did you set the DelayValidation property of the Excel connection manager to true?

Some where you need to maintain the holidays as well; With in your SSIS, run a SQL task and run your procedure only if it is not a holiday 🙂

You may maintain the list of files in a table, read them into a ADO records set. In the For each control load the name of file into a variable,...

Merge join is the right choice here. If you are facing any discripencies in the result set, do check for the null values in your mappings; and make sure source...

Verify 'Input and Output Properties' of your 'County' componenet. I guess length of the Column in 'Output Columns' is lesser then the length specified in 'Input Columns'.

Given that the Groups in SSRS work on a hierarchy model, you may not meet the requirement with Single Tablix.

"show only when value [Qry] when it is greater than 1 after combining the table"

you need not use a aggregate function to achieve this.

HAVING [Qry] > 1 will work.